ISO19111: remove PROJ.5 specific format for CRS (refs #1214)

As discussed in https://github.com/OSGeo/proj.4/issues/1214#issuecomment-452084720,
the introduction of a new PROJ.5 format to export CRS using pipeline/unitconvert/axisswap
as an attempt of improving the PROJ.4 format used by GDAL and other products is
likely a dead-end since it is still lossy in many aspects and can cause confusion
with coodinate operations.

Consequently the PROJ_5 convention will be identical to PROJ_4 for CRS export.

Note: on the import side, I've kept the code that could parse unitconvert and
axisswap when building a CRS definition from a pipeline. It is there as a hidden
feature as it was kind of a tear to remove that code in case it might still be
useful...

7 files changed, 254 insertions, 319 deletions

diff --git a/test/cli/testprojinfo_out.dist b/test/cli/testprojinfo_out.dist
index 1fd3bbbf..3d70bd99 100644
--- a/test/cli/testprojinfo_out.dist
+++ b/test/cli/testprojinfo_out.dist
@@ -1,6 +1,6 @@
 Testing projinfo EPSG:4326
 PROJ string:
-+proj=pipeline +step +proj=longlat +ellps=WGS84 +step +proj=unitconvert +xy_in=rad +xy_out=deg +step +proj=axisswap +order=2,1
++proj=longlat +datum=WGS84 +no_defs
 
 WKT2_2015 string:
 GEODCRS["WGS 84",
@@ -22,9 +22,6 @@ GEODCRS["WGS 84",
 
 Testing projinfo -o ALL EPSG:4326
 PROJ string:
-+proj=pipeline +step +proj=longlat +ellps=WGS84 +step +proj=unitconvert +xy_in=rad +xy_out=deg +step +proj=axisswap +order=2,1
-
-PROJ.4 string:
 +proj=longlat +datum=WGS84 +no_defs
 
 WKT2_2015 string:
@@ -484,7 +481,7 @@ Alternative non-deprecated CRS:
   EPSG:3003
 
 PROJ string:
-+proj=pipeline +step +proj=axisswap +order=2,1 +step +proj=unitconvert +xy_in=deg +xy_out=rad +step +inv +proj=longlat +ellps=intl +pm=rome +step +proj=tmerc +lat_0=0 +lon_0=9 +k=0.9996 +x_0=1500000 +y_0=0 +ellps=intl +pm=rome
++proj=tmerc +lat_0=0 +lon_0=9 +k=0.9996 +x_0=1500000 +y_0=0 +ellps=intl +pm=rome +units=m +no_defs
 
 WKT2_2015 string:
 PROJCRS["Monte Mario (Rome) / Italy zone 1",
@@ -529,7 +526,7 @@ Warning: Parsing error : syntax error, unexpected UNIT, expecting PRIMEM. Error
 HEROID["WGS 84",6378137,298.257223563]],UNIT["degree",0.0174532925199433]]
                                         ^
 PROJ string:
-+proj=pipeline +step +proj=longlat +ellps=WGS84 +step +proj=unitconvert +xy_in=rad +xy_out=deg
++proj=longlat +datum=WGS84 +no_defs
 
 WKT2_2015 string:
 GEODCRS["WGS 84",
diff --git a/test/unit/proj_angular_io_test.cpp b/test/unit/proj_angular_io_test.cpp
index fdb44704..dbf09986 100644
--- a/test/unit/proj_angular_io_test.cpp
+++ b/test/unit/proj_angular_io_test.cpp
@@ -48,7 +48,9 @@ TEST(AngularUnits, Basic) {
 
 TEST(AngularUnits, Pipelines) {
     auto ctx = proj_context_create();
-    auto P = proj_create(ctx, "proj=pipeline +step +proj=axisswap +order=2,1 +step +proj=latlong +step +proj=axisswap +order=2,1");
+    auto P =
+        proj_create(ctx, "proj=pipeline +step +proj=axisswap +order=2,1 +step "
+                         "+proj=latlong +step +proj=axisswap +order=2,1");
 
     EXPECT_TRUE(proj_angular_input(P, PJ_FWD));
     EXPECT_TRUE(proj_angular_output(P, PJ_FWD));
@@ -57,45 +59,43 @@ TEST(AngularUnits, Pipelines) {
 
     proj_destroy(P);
     proj_context_destroy(ctx);
-
 }
 
 TEST(AngularUnits, Pipelines2) {
     auto ctx = proj_context_create();
     auto P = proj_create(
-            ctx,
-            "+proj=pipeline "
-            "+step +proj=axisswap +order=2,1 "
-            "+step +proj=unitconvert +xy_in=deg +xy_out=rad "
-            "+step +proj=tmerc +lat_0=0 +lon_0=-81 +k=0.9996 +x_0=500000.001016002 +y_0=0 +ellps=WGS84 "
-            "+step +proj=axisswap +order=2,1 "
-            "+step +proj=unitconvert +xy_in=m +z_in=m +xy_out=us-ft +z_out=us-ft");
+        ctx,
+        "+proj=pipeline "
+        "+step +proj=axisswap +order=2,1 "
+        "+step +proj=unitconvert +xy_in=deg +xy_out=rad "
+        "+step +proj=tmerc +lat_0=0 +lon_0=-81 +k=0.9996 +x_0=500000.001016002 "
+        "+y_0=0 +ellps=WGS84 "
+        "+step +proj=axisswap +order=2,1 "
+        "+step +proj=unitconvert +xy_in=m +z_in=m +xy_out=us-ft +z_out=us-ft");
 
     EXPECT_FALSE(proj_angular_input(P, PJ_FWD));
     EXPECT_FALSE(proj_angular_output(P, PJ_FWD));
 
     proj_destroy(P);
     proj_context_destroy(ctx);
-
 }
 
 TEST(AngularUnits, Pipelines3) {
     auto ctx = proj_context_create();
     auto P = proj_create(
-            ctx,
-            "+proj=pipeline "
-            "+step +proj=axisswap +order=2,1 "
-            "+step +proj=tmerc +lat_0=0 +lon_0=-81 +k=0.9996 +x_0=500000.001016002 +y_0=0 +ellps=WGS84 "
-            "+step +proj=axisswap +order=2,1 "
-            "+step +proj=unitconvert +xy_in=m +z_in=m +xy_out=us-ft +z_out=us-ft");
+        ctx,
+        "+proj=pipeline "
+        "+step +proj=axisswap +order=2,1 "
+        "+step +proj=tmerc +lat_0=0 +lon_0=-81 +k=0.9996 +x_0=500000.001016002 "
+        "+y_0=0 +ellps=WGS84 "
+        "+step +proj=axisswap +order=2,1 "
+        "+step +proj=unitconvert +xy_in=m +z_in=m +xy_out=us-ft +z_out=us-ft");
 
     EXPECT_TRUE(proj_angular_input(P, PJ_FWD));
     EXPECT_FALSE(proj_angular_output(P, PJ_FWD));
 
     proj_destroy(P);
     proj_context_destroy(ctx);
-
 }
 
-
 } // namespace
diff --git a/test/unit/test_c_api.cpp b/test/unit/test_c_api.cpp
index 82cb7b75..6353d46f 100644
--- a/test/unit/test_c_api.cpp
+++ b/test/unit/test_c_api.cpp
@@ -492,10 +492,7 @@ TEST_F(CApi, proj_as_proj_string) {
     {
         auto proj_5 = proj_as_proj_string(m_ctxt, obj, PJ_PROJ_5, nullptr);
         ASSERT_NE(proj_5, nullptr);
-        EXPECT_EQ(std::string(proj_5), "+proj=pipeline +step +proj=longlat "
-                                       "+ellps=WGS84 +step +proj=unitconvert "
-                                       "+xy_in=rad +xy_out=deg +step "
-                                       "+proj=axisswap +order=2,1");
+        EXPECT_EQ(std::string(proj_5), "+proj=longlat +datum=WGS84 +no_defs");
     }
     {
         auto proj_4 = proj_as_proj_string(m_ctxt, obj, PJ_PROJ_4, nullptr);
diff --git a/test/unit/test_crs.cpp b/test/unit/test_crs.cpp
index fe0ac7e8..d694d297 100644
--- a/test/unit/test_crs.cpp
+++ b/test/unit/test_crs.cpp
@@ -388,14 +388,7 @@ TEST(crs, EPSG_4326_as_WKT1_ESRI_without_database) {
 TEST(crs, EPSG_4326_as_PROJ_string) {
     auto crs = GeographicCRS::EPSG_4326;
     EXPECT_EQ(crs->exportToPROJString(PROJStringFormatter::create().get()),
-              "+proj=pipeline +step +proj=longlat +ellps=WGS84 +step "
-              "+proj=unitconvert +xy_in=rad +xy_out=deg +step +proj=axisswap "
-              "+order=2,1");
-    EXPECT_EQ(
-        crs->exportToPROJString(
-            PROJStringFormatter::create(PROJStringFormatter::Convention::PROJ_4)
-                .get()),
-        "+proj=longlat +datum=WGS84 +no_defs");
+              "+proj=longlat +datum=WGS84 +no_defs");
 }
 
 // ---------------------------------------------------------------------------
@@ -595,14 +588,7 @@ TEST(crs, EPSG_4807_as_WKT1_ESRI_without_database) {
 TEST(crs, EPSG_4807_as_PROJ_string) {
     auto crs = GeographicCRS::EPSG_4807;
     EXPECT_EQ(crs->exportToPROJString(PROJStringFormatter::create().get()),
-              "+proj=pipeline +step +proj=longlat +ellps=clrk80ign "
-              "+pm=paris +step +proj=unitconvert +xy_in=rad +xy_out=grad +step "
-              "+proj=axisswap +order=2,1");
-    EXPECT_EQ(
-        crs->exportToPROJString(
-            PROJStringFormatter::create(PROJStringFormatter::Convention::PROJ_4)
-                .get()),
-        "+proj=longlat +ellps=clrk80ign +pm=paris +no_defs");
+              "+proj=longlat +ellps=clrk80ign +pm=paris +no_defs");
 }
 
 // ---------------------------------------------------------------------------
@@ -624,11 +610,8 @@ TEST(crs, EPSG_4267) {
               "            ORDER[2],\n"
               "            ANGLEUNIT[\"degree\",0.0174532925199433]],\n"
               "    ID[\"EPSG\",4267]]");
-    EXPECT_EQ(
-        crs->exportToPROJString(
-            PROJStringFormatter::create(PROJStringFormatter::Convention::PROJ_4)
-                .get()),
-        "+proj=longlat +datum=NAD27 +no_defs");
+    EXPECT_EQ(crs->exportToPROJString(PROJStringFormatter::create().get()),
+              "+proj=longlat +datum=NAD27 +no_defs");
 }
 
 // ---------------------------------------------------------------------------
@@ -663,11 +646,8 @@ TEST(crs, EPSG_4269) {
               "            ORDER[2],\n"
               "            ANGLEUNIT[\"degree\",0.0174532925199433]],\n"
               "    ID[\"EPSG\",4269]]");
-    EXPECT_EQ(
-        crs->exportToPROJString(
-            PROJStringFormatter::create(PROJStringFormatter::Convention::PROJ_4)
-                .get()),
-        "+proj=longlat +datum=NAD83 +no_defs");
+    EXPECT_EQ(crs->exportToPROJString(PROJStringFormatter::create().get()),
+              "+proj=longlat +datum=NAD83 +no_defs");
 }
 
 // ---------------------------------------------------------------------------
@@ -725,15 +705,6 @@ TEST(crs, EPSG_27561_projected_with_geodetic_in_grad_as_PROJ_string_and_WKT1) {
     ASSERT_TRUE(crs != nullptr);
     EXPECT_EQ(
         crs->exportToPROJString(PROJStringFormatter::create().get()),
-        "+proj=pipeline +step +proj=axisswap +order=2,1 +step "
-        "+proj=unitconvert +xy_in=grad +xy_out=rad +step +inv +proj=longlat "
-        "+ellps=clrk80ign +pm=paris +step +proj=lcc +lat_1=49.5 "
-        "+lat_0=49.5 +lon_0=0 +k_0=0.999877341 +x_0=600000 +y_0=200000 "
-        "+ellps=clrk80ign +pm=paris");
-    EXPECT_EQ(
-        crs->exportToPROJString(
-            PROJStringFormatter::create(PROJStringFormatter::Convention::PROJ_4)
-                .get()),
         "+proj=lcc +lat_1=49.5 +lat_0=49.5 +lon_0=0 +k_0=0.999877341 "
         "+x_0=600000 +y_0=200000 +ellps=clrk80ign +pm=paris +units=m +no_defs");
 
@@ -811,9 +782,7 @@ TEST(crs, EPSG_3040_projected_northing_easting_as_PROJ_string) {
     auto crs = nn_dynamic_pointer_cast<ProjectedCRS>(obj);
     ASSERT_TRUE(crs != nullptr);
     EXPECT_EQ(crs->exportToPROJString(PROJStringFormatter::create().get()),
-              "+proj=pipeline +step +proj=axisswap +order=2,1 +step "
-              "+proj=unitconvert +xy_in=deg +xy_out=rad +step +proj=utm "
-              "+zone=28 +ellps=GRS80 +step +proj=axisswap +order=2,1");
+              "+proj=utm +zone=28 +ellps=GRS80 +units=m +no_defs");
 }
 
 // ---------------------------------------------------------------------------
@@ -843,17 +812,8 @@ TEST(crs, EPSG_2222_projected_unit_foot_as_PROJ_string_and_WKT1) {
     auto crs = nn_dynamic_pointer_cast<ProjectedCRS>(obj);
     ASSERT_TRUE(crs != nullptr);
     EXPECT_EQ(crs->exportToPROJString(PROJStringFormatter::create().get()),
-              "+proj=pipeline +step +proj=axisswap +order=2,1 +step "
-              "+proj=unitconvert +xy_in=deg +xy_out=rad +step +proj=tmerc "
-              "+lat_0=31 +lon_0=-110.166666666667 +k=0.9999 +x_0=213360 "
-              "+y_0=0 +ellps=GRS80 +step +proj=unitconvert +xy_in=m +z_in=m "
-              "+xy_out=ft +z_out=ft");
-    EXPECT_EQ(
-        crs->exportToPROJString(
-            PROJStringFormatter::create(PROJStringFormatter::Convention::PROJ_4)
-                .get()),
-        "+proj=tmerc +lat_0=31 +lon_0=-110.166666666667 +k=0.9999 "
-        "+x_0=213360 +y_0=0 +datum=NAD83 +units=ft +no_defs");
+              "+proj=tmerc +lat_0=31 +lon_0=-110.166666666667 +k=0.9999 "
+              "+x_0=213360 +y_0=0 +datum=NAD83 +units=ft +no_defs");
 
     auto wkt1 = crs->exportToWKT(
         WKTFormatter::create(WKTFormatter::Convention::WKT1_GDAL).get());
@@ -931,22 +891,18 @@ TEST(crs, EPSG_32661_projected_north_pole_north_east) {
     auto crs = factory->createCoordinateReferenceSystem("32661");
     auto proj_crs = nn_dynamic_pointer_cast<ProjectedCRS>(crs);
     ASSERT_TRUE(proj_crs != nullptr);
+
     auto proj_string =
         "+proj=pipeline +step +proj=axisswap +order=2,1 +step "
         "+proj=unitconvert +xy_in=deg +xy_out=rad +step +proj=stere "
         "+lat_0=90 +lon_0=0 +k=0.994 +x_0=2000000 +y_0=2000000 "
         "+ellps=WGS84 +step +proj=axisswap +order=2,1";
-    EXPECT_EQ(proj_crs->exportToPROJString(PROJStringFormatter::create().get()),
-              proj_string);
 
-    auto obj_from_proj = PROJStringParser().createFromPROJString(proj_string);
-    auto crs_from_proj = nn_dynamic_pointer_cast<ProjectedCRS>(obj_from_proj);
-    ASSERT_TRUE(crs_from_proj != nullptr);
-    EXPECT_EQ(
-        crs_from_proj->exportToPROJString(PROJStringFormatter::create().get()),
-        proj_string);
-    EXPECT_TRUE(crs_from_proj->coordinateSystem()->isEquivalentTo(
-        proj_crs->coordinateSystem().get()));
+    auto op = CoordinateOperationFactory::create()->createOperation(
+        GeographicCRS::EPSG_4326, NN_NO_CHECK(proj_crs));
+    ASSERT_TRUE(op != nullptr);
+    EXPECT_EQ(op->exportToPROJString(PROJStringFormatter::create().get()),
+              proj_string);
 }
 
 // ---------------------------------------------------------------------------
@@ -962,17 +918,12 @@ TEST(crs, EPSG_5041_projected_north_pole_east_north) {
         "+proj=unitconvert +xy_in=deg +xy_out=rad +step +proj=stere "
         "+lat_0=90 +lon_0=0 +k=0.994 +x_0=2000000 +y_0=2000000 "
         "+ellps=WGS84";
-    EXPECT_EQ(proj_crs->exportToPROJString(PROJStringFormatter::create().get()),
-              proj_string);
 
-    auto obj_from_proj = PROJStringParser().createFromPROJString(proj_string);
-    auto crs_from_proj = nn_dynamic_pointer_cast<ProjectedCRS>(obj_from_proj);
-    ASSERT_TRUE(crs_from_proj != nullptr);
-    EXPECT_EQ(
-        crs_from_proj->exportToPROJString(PROJStringFormatter::create().get()),
-        proj_string);
-    EXPECT_TRUE(crs_from_proj->coordinateSystem()->isEquivalentTo(
-        proj_crs->coordinateSystem().get()));
+    auto op = CoordinateOperationFactory::create()->createOperation(
+        GeographicCRS::EPSG_4326, NN_NO_CHECK(proj_crs));
+    ASSERT_TRUE(op != nullptr);
+    EXPECT_EQ(op->exportToPROJString(PROJStringFormatter::create().get()),
+              proj_string);
 }
 
 // ---------------------------------------------------------------------------
@@ -988,17 +939,12 @@ TEST(crs, EPSG_32761_projected_south_pole_north_east) {
         "+proj=unitconvert +xy_in=deg +xy_out=rad +step +proj=stere "
         "+lat_0=-90 +lon_0=0 +k=0.994 +x_0=2000000 +y_0=2000000 "
         "+ellps=WGS84 +step +proj=axisswap +order=2,1";
-    EXPECT_EQ(proj_crs->exportToPROJString(PROJStringFormatter::create().get()),
-              proj_string);
 
-    auto obj_from_proj = PROJStringParser().createFromPROJString(proj_string);
-    auto crs_from_proj = nn_dynamic_pointer_cast<ProjectedCRS>(obj_from_proj);
-    ASSERT_TRUE(crs_from_proj != nullptr);
-    EXPECT_EQ(
-        crs_from_proj->exportToPROJString(PROJStringFormatter::create().get()),
-        proj_string);
-    EXPECT_TRUE(crs_from_proj->coordinateSystem()->isEquivalentTo(
-        proj_crs->coordinateSystem().get()));
+    auto op = CoordinateOperationFactory::create()->createOperation(
+        GeographicCRS::EPSG_4326, NN_NO_CHECK(proj_crs));
+    ASSERT_TRUE(op != nullptr);
+    EXPECT_EQ(op->exportToPROJString(PROJStringFormatter::create().get()),
+              proj_string);
 }
 
 // ---------------------------------------------------------------------------
@@ -1009,11 +955,17 @@ TEST(crs, EPSG_5042_projected_south_pole_east_north) {
     auto crs = factory->createCoordinateReferenceSystem("5042");
     auto proj_crs = nn_dynamic_pointer_cast<ProjectedCRS>(crs);
     ASSERT_TRUE(proj_crs != nullptr);
-    EXPECT_EQ(proj_crs->exportToPROJString(PROJStringFormatter::create().get()),
-              "+proj=pipeline +step +proj=axisswap +order=2,1 +step "
-              "+proj=unitconvert +xy_in=deg +xy_out=rad +step +proj=stere "
-              "+lat_0=-90 +lon_0=0 +k=0.994 +x_0=2000000 +y_0=2000000 "
-              "+ellps=WGS84");
+    auto proj_string =
+        "+proj=pipeline +step +proj=axisswap +order=2,1 +step "
+        "+proj=unitconvert +xy_in=deg +xy_out=rad +step +proj=stere "
+        "+lat_0=-90 +lon_0=0 +k=0.994 +x_0=2000000 +y_0=2000000 "
+        "+ellps=WGS84";
+
+    auto op = CoordinateOperationFactory::create()->createOperation(
+        GeographicCRS::EPSG_4326, NN_NO_CHECK(proj_crs));
+    ASSERT_TRUE(op != nullptr);
+    EXPECT_EQ(op->exportToPROJString(PROJStringFormatter::create().get()),
+              proj_string);
 }
 
 // ---------------------------------------------------------------------------
@@ -1157,12 +1109,7 @@ TEST(crs, EPSG_4978_as_WKT1_GDAL_with_database) {
 TEST(crs, geocentricCRS_as_PROJ_string) {
     auto crs = createGeocentric();
     EXPECT_EQ(crs->exportToPROJString(PROJStringFormatter::create().get()),
-              "+proj=cart +ellps=WGS84");
-    EXPECT_EQ(
-        crs->exportToPROJString(
-            PROJStringFormatter::create(PROJStringFormatter::Convention::PROJ_4)
-                .get()),
-        "+proj=geocent +datum=WGS84 +units=m +no_defs");
+              "+proj=geocent +datum=WGS84 +units=m +no_defs");
 }
 
 // ---------------------------------------------------------------------------
@@ -1173,14 +1120,17 @@ TEST(crs, geocentricCRS_non_meter_unit_as_PROJ_string) {
         CartesianCS::createGeocentric(
             UnitOfMeasure("kilometre", 1000.0, UnitOfMeasure::Type::LINEAR)));
 
-    EXPECT_EQ(crs->exportToPROJString(PROJStringFormatter::create().get()),
-              "+proj=pipeline +step +proj=cart +ellps=WGS84 +step "
-              "+proj=unitconvert +xy_in=m +z_in=m +xy_out=km +z_out=km");
-    EXPECT_THROW(
-        crs->exportToPROJString(
-            PROJStringFormatter::create(PROJStringFormatter::Convention::PROJ_4)
-                .get()),
-        FormattingException);
+    auto op = CoordinateOperationFactory::create()->createOperation(
+        GeographicCRS::EPSG_4326, crs);
+    ASSERT_TRUE(op != nullptr);
+    EXPECT_EQ(op->exportToPROJString(PROJStringFormatter::create().get()),
+              "+proj=pipeline +step +proj=axisswap +order=2,1 +step "
+              "+proj=unitconvert +xy_in=deg +xy_out=rad +step +proj=cart "
+              "+ellps=WGS84 +step +proj=unitconvert +xy_in=m +z_in=m "
+              "+xy_out=km +z_out=km");
+
+    EXPECT_THROW(crs->exportToPROJString(PROJStringFormatter::create().get()),
+                 FormattingException);
 }
 
 // ---------------------------------------------------------------------------
@@ -1191,9 +1141,14 @@ TEST(crs, geocentricCRS_unsupported_unit_as_PROJ_string) {
         CartesianCS::createGeocentric(
             UnitOfMeasure("my unit", 500.0, UnitOfMeasure::Type::LINEAR)));
 
-    EXPECT_EQ(crs->exportToPROJString(PROJStringFormatter::create().get()),
-              "+proj=pipeline +step +proj=cart +ellps=WGS84 +step "
-              "+proj=unitconvert +xy_in=m +z_in=m +xy_out=500 +z_out=500");
+    auto op = CoordinateOperationFactory::create()->createOperation(
+        GeographicCRS::EPSG_4326, crs);
+    ASSERT_TRUE(op != nullptr);
+    EXPECT_EQ(op->exportToPROJString(PROJStringFormatter::create().get()),
+              "+proj=pipeline +step +proj=axisswap +order=2,1 +step "
+              "+proj=unitconvert +xy_in=deg +xy_out=rad +step +proj=cart "
+              "+ellps=WGS84 +step +proj=unitconvert +xy_in=m +z_in=m "
+              "+xy_out=500 +z_out=500");
 }
 
 // ---------------------------------------------------------------------------
@@ -1556,7 +1511,7 @@ TEST(crs, projectedCRS_shallowClone) {
         }
         EXPECT_EQ(clone->baseCRS()->exportToPROJString(
                       PROJStringFormatter::create().get()),
-                  "+proj=cart +ellps=WGS84");
+                  "+proj=geocent +datum=WGS84 +units=m +no_defs");
     }
 }
 
@@ -1785,15 +1740,16 @@ TEST(crs, projectedCRS_from_WKT1_ESRI_as_WKT1_ESRI) {
 
 TEST(crs, projectedCRS_as_PROJ_string) {
     auto crs = createProjected();
-    EXPECT_EQ(crs->exportToPROJString(PROJStringFormatter::create().get()),
+
+    auto op = CoordinateOperationFactory::create()->createOperation(
+        GeographicCRS::EPSG_4326, crs);
+    ASSERT_TRUE(op != nullptr);
+    EXPECT_EQ(op->exportToPROJString(PROJStringFormatter::create().get()),
               "+proj=pipeline +step +proj=axisswap +order=2,1 +step "
               "+proj=unitconvert +xy_in=deg +xy_out=rad +step +proj=utm "
               "+zone=31 +ellps=WGS84");
-    EXPECT_EQ(
-        crs->exportToPROJString(
-            PROJStringFormatter::create(PROJStringFormatter::Convention::PROJ_4)
-                .get()),
-        "+proj=utm +zone=31 +datum=WGS84 +units=m +no_defs");
+    EXPECT_EQ(crs->exportToPROJString(PROJStringFormatter::create().get()),
+              "+proj=utm +zone=31 +datum=WGS84 +units=m +no_defs");
 }
 
 // ---------------------------------------------------------------------------
@@ -1802,7 +1758,10 @@ TEST(crs, projectedCRS_Krovak_EPSG_5221_as_PROJ_string) {
     auto factory = AuthorityFactory::create(DatabaseContext::create(), "EPSG");
     auto crs = factory->createProjectedCRS("5221");
     // 30deg 17' 17.30311'' = 30.28813975277777776
-    EXPECT_EQ(crs->exportToPROJString(PROJStringFormatter::create().get()),
+    auto op = CoordinateOperationFactory::create()->createOperation(
+        crs->baseCRS(), crs);
+    ASSERT_TRUE(op != nullptr);
+    EXPECT_EQ(op->exportToPROJString(PROJStringFormatter::create().get()),
               "+proj=pipeline +step +proj=axisswap +order=2,1 "
               "+step +proj=unitconvert +xy_in=deg +xy_out=rad "
               "+step +inv +proj=longlat +ellps=bessel +pm=ferro "
@@ -1819,7 +1778,10 @@ TEST(crs, projectedCRS_Krovak_with_approximate_alpha_as_PROJ_string) {
         "+proj=krovak +lat_0=49.5 +lon_0=42.5 +alpha=30.28813972222222 "
         "+k=0.9999 +x_0=0 +y_0=0 +ellps=bessel +pm=ferro +units=m +no_defs");
     auto crs = nn_dynamic_pointer_cast<ProjectedCRS>(obj);
-    EXPECT_EQ(crs->exportToPROJString(PROJStringFormatter::create().get()),
+    auto op = CoordinateOperationFactory::create()->createOperation(
+        crs->baseCRS(), NN_NO_CHECK(crs));
+    ASSERT_TRUE(op != nullptr);
+    EXPECT_EQ(op->exportToPROJString(PROJStringFormatter::create().get()),
               "+proj=pipeline "
               "+step +proj=unitconvert +xy_in=deg +xy_out=rad "
               "+step +inv +proj=longlat +ellps=bessel +pm=ferro "
@@ -3159,17 +3121,8 @@ TEST(crs, compoundCRS_as_WKT1_GDAL) {
 
 TEST(crs, compoundCRS_as_PROJ_string) {
     auto crs = createCompoundCRS();
-    auto expected = "+proj=pipeline +step +proj=axisswap +order=2,1 +step "
-                    "+proj=unitconvert +xy_in=deg +xy_out=rad +step +proj=utm "
-                    "+zone=31 +ellps=WGS84 +vunits=m";
-
     EXPECT_EQ(crs->exportToPROJString(PROJStringFormatter::create().get()),
-              expected);
-    EXPECT_EQ(
-        crs->exportToPROJString(
-            PROJStringFormatter::create(PROJStringFormatter::Convention::PROJ_4)
-                .get()),
-        "+proj=utm +zone=31 +datum=WGS84 +units=m +vunits=m +no_defs");
+              "+proj=utm +zone=31 +datum=WGS84 +units=m +vunits=m +no_defs");
 }
 
 // ---------------------------------------------------------------------------
@@ -4022,8 +3975,11 @@ TEST(crs, derivedGeographicCRS_to_PROJ) {
     auto obj = WKTParser().createFromWKT(wkt);
     auto crs = nn_dynamic_pointer_cast<DerivedGeographicCRS>(obj);
     ASSERT_TRUE(crs != nullptr);
+    auto op = CoordinateOperationFactory::create()->createOperation(
+        crs->baseCRS(), NN_NO_CHECK(crs));
+    ASSERT_TRUE(op != nullptr);
     EXPECT_EQ(
-        crs->exportToPROJString(PROJStringFormatter::create().get()),
+        op->exportToPROJString(PROJStringFormatter::create().get()),
         "+proj=pipeline +step +proj=axisswap +order=2,1 +step "
         "+proj=unitconvert +xy_in=deg +xy_out=rad +step +proj=ob_tran "
         "+o_proj=longlat +o_lat_p=52 +o_lon_p=-30 +lon_0=-25 +ellps=WGS84 "
@@ -4071,7 +4027,10 @@ TEST(crs, derivedGeographicCRS_with_affine_transform_to_PROJ) {
     auto crs = nn_dynamic_pointer_cast<DerivedGeographicCRS>(obj);
     ASSERT_TRUE(crs != nullptr);
     EXPECT_TRUE(crs->derivingConversion()->validateParameters().empty());
-    EXPECT_EQ(crs->exportToPROJString(PROJStringFormatter::create().get()),
+    auto op = CoordinateOperationFactory::create()->createOperation(
+        crs->baseCRS(), NN_NO_CHECK(crs));
+    ASSERT_TRUE(op != nullptr);
+    EXPECT_EQ(op->exportToPROJString(PROJStringFormatter::create().get()),
               "+proj=affine +xoff=0.5 +s11=1 +s12=0 +yoff=2.5 +s21=0 +s22=1");
 }
 
@@ -4254,15 +4213,6 @@ TEST(crs, derivedProjectedCRS_WKT2_2015) {
 
 // ---------------------------------------------------------------------------
 
-TEST(crs, derivedProjectedCRS_to_PROJ) {
-
-    auto crs = createDerivedProjectedCRS();
-    EXPECT_EQ(crs->exportToPROJString(PROJStringFormatter::create().get()),
-              "+proj=unimplemented");
-}
-
-// ---------------------------------------------------------------------------
-
 static DateTimeTemporalCSNNPtr createDateTimeTemporalCS() {
     return DateTimeTemporalCS::create(
         PropertyMap(),
diff --git a/test/unit/test_factory.cpp b/test/unit/test_factory.cpp
index deff6b63..e9b29728 100644
--- a/test/unit/test_factory.cpp
+++ b/test/unit/test_factory.cpp
@@ -409,9 +409,7 @@ TEST(factory, AuthorityFactory_createGeodeticCRS_geographic2D) {
     EXPECT_TRUE(extent->isEquivalentTo(factory->createExtent("1262").get()));
 
     EXPECT_EQ(crs->exportToPROJString(PROJStringFormatter::create().get()),
-              "+proj=pipeline +step +proj=longlat +ellps=WGS84 +step "
-              "+proj=unitconvert +xy_in=rad +xy_out=deg +step +proj=axisswap "
-              "+order=2,1");
+              "+proj=longlat +datum=WGS84 +no_defs");
 }
 
 // ---------------------------------------------------------------------------
@@ -972,11 +970,9 @@ TEST(factory, AuthorityFactory_test_uom_9110) {
     // This tests conversion from unit of measure EPSG:9110 DDD.MMSSsss
     auto crs = factory->createProjectedCRS("2172");
     EXPECT_EQ(crs->exportToPROJString(PROJStringFormatter::create().get()),
-              "+proj=pipeline +step +proj=axisswap +order=2,1 +step "
-              "+proj=unitconvert +xy_in=deg +xy_out=rad +step +proj=sterea "
-              "+lat_0=53.0019444444444 +lon_0=21.5027777777778 +k=0.9998 "
-              "+x_0=4603000 +y_0=5806000 +ellps=krass +step +proj=axisswap "
-              "+order=2,1");
+              "+proj=sterea +lat_0=53.0019444444444 +lon_0=21.5027777777778 "
+              "+k=0.9998 +x_0=4603000 +y_0=5806000 +ellps=krass +units=m "
+              "+no_defs");
 }
 
 // ---------------------------------------------------------------------------
@@ -2327,10 +2323,8 @@ TEST_F(FactoryWithTmpDatabase, custom_projected_crs) {
         EXPECT_EQ(*(crs->name()->description()), "my name");
         EXPECT_EQ(crs->identifiers().size(), 1);
         EXPECT_EQ(crs->derivingConversion()->targetCRS().get(), crs.get());
-        EXPECT_EQ(
-            crs->exportToPROJString(PROJStringFormatter::create().get()),
-            "+proj=pipeline +step +proj=unitconvert +xy_in=deg +xy_out=rad "
-            "+step +proj=mbt_s +unused_flag +ellps=WGS84");
+        EXPECT_EQ(crs->exportToPROJString(PROJStringFormatter::create().get()),
+                  "+proj=mbt_s +unused_flag +datum=WGS84 +units=m +no_defs");
         EXPECT_TRUE(crs->canonicalBoundCRS() == nullptr);
     }
     {
@@ -2338,10 +2332,8 @@ TEST_F(FactoryWithTmpDatabase, custom_projected_crs) {
         EXPECT_EQ(*(crs->name()->description()), "my name");
         EXPECT_EQ(crs->identifiers().size(), 1);
         EXPECT_EQ(crs->derivingConversion()->targetCRS().get(), crs.get());
-        EXPECT_EQ(
-            crs->exportToPROJString(PROJStringFormatter::create().get()),
-            "+proj=pipeline +step +proj=unitconvert +xy_in=deg +xy_out=rad "
-            "+step +proj=mbt_s +unused_flag +ellps=WGS84");
+        EXPECT_EQ(crs->exportToPROJString(PROJStringFormatter::create().get()),
+                  "+proj=mbt_s +unused_flag +datum=WGS84 +units=m +no_defs");
         EXPECT_TRUE(crs->canonicalBoundCRS() != nullptr);
     }
 
diff --git a/test/unit/test_io.cpp b/test/unit/test_io.cpp
index fc20b08d..3eabfc03 100644
--- a/test/unit/test_io.cpp
+++ b/test/unit/test_io.cpp
@@ -1253,11 +1253,10 @@ TEST(wkt_parse, wkt1_krovak_south_west) {
 
     auto projString =
         crs->exportToPROJString(PROJStringFormatter::create().get());
-    auto expectedPROJString =
-        "+proj=pipeline +step +proj=unitconvert +xy_in=deg +xy_out=rad "
-        "+step +proj=krovak +axis=swu +lat_0=49.5 "
-        "+lon_0=24.8333333333333 +alpha=30.2881397222222 "
-        "+k=0.9999 +x_0=0 +y_0=0 +ellps=bessel";
+    auto expectedPROJString = "+proj=krovak +axis=swu +lat_0=49.5 "
+                              "+lon_0=24.8333333333333 +alpha=30.2881397222222 "
+                              "+k=0.9999 +x_0=0 +y_0=0 +ellps=bessel +units=m "
+                              "+no_defs";
     EXPECT_EQ(projString, expectedPROJString);
 
     obj = PROJStringParser().createFromPROJString(projString);
@@ -1368,9 +1367,9 @@ TEST(wkt_parse, wkt1_krovak_north_oriented) {
         "    ID[\"EPSG\",5514]]");
 
     EXPECT_EQ(crs->exportToPROJString(PROJStringFormatter::create().get()),
-              "+proj=pipeline +step +proj=unitconvert +xy_in=deg +xy_out=rad "
-              "+step +proj=krovak +lat_0=49.5 +lon_0=24.8333333333333 "
-              "+alpha=30.2881397222222 +k=0.9999 +x_0=0 +y_0=0 +ellps=bessel");
+              "+proj=krovak +lat_0=49.5 +lon_0=24.8333333333333 "
+              "+alpha=30.2881397222222 +k=0.9999 +x_0=0 +y_0=0 +ellps=bessel "
+              "+units=m +no_defs");
 }
 
 // ---------------------------------------------------------------------------
@@ -6892,17 +6891,20 @@ TEST(io, projparse_longlat_pm_overriding_datum) {
 
 TEST(io, projparse_longlat_complex) {
     std::string input =
-        "+proj=pipeline +step +proj=longlat +ellps=clrk80ign "
+        "+step +proj=longlat +ellps=clrk80ign "
         "+pm=paris +step +proj=unitconvert +xy_in=rad +xy_out=grad +step "
         "+proj=axisswap +order=2,1";
-    auto obj = PROJStringParser().createFromPROJString(input);
+    auto obj =
+        PROJStringParser().createFromPROJString("+proj=pipeline " + input);
     auto crs = nn_dynamic_pointer_cast<GeographicCRS>(obj);
     ASSERT_TRUE(crs != nullptr);
-    EXPECT_EQ(
-        crs->exportToPROJString(
-            PROJStringFormatter::create(PROJStringFormatter::Convention::PROJ_5)
-                .get()),
-        input);
+    auto op = CoordinateOperationFactory::create()->createOperation(
+        GeographicCRS::EPSG_4326, NN_NO_CHECK(crs));
+    ASSERT_TRUE(op != nullptr);
+    EXPECT_EQ(op->exportToPROJString(PROJStringFormatter::create().get()),
+              "+proj=pipeline +step +proj=axisswap +order=2,1 +step "
+              "+proj=unitconvert +xy_in=deg +xy_out=rad " +
+                  input);
 }
 
 // ---------------------------------------------------------------------------
@@ -7069,7 +7071,7 @@ TEST(io, projparse_vunits) {
     auto crs = nn_dynamic_pointer_cast<VerticalCRS>(obj);
     ASSERT_TRUE(crs != nullptr);
     EXPECT_EQ(crs->exportToPROJString(PROJStringFormatter::create().get()),
-              "+vunits=ft");
+              "+vunits=ft +no_defs");
 }
 
 // ---------------------------------------------------------------------------
@@ -7079,7 +7081,7 @@ TEST(io, projparse_vto_meter) {
     auto crs = nn_dynamic_pointer_cast<VerticalCRS>(obj);
     ASSERT_TRUE(crs != nullptr);
     EXPECT_EQ(crs->exportToPROJString(PROJStringFormatter::create().get()),
-              "+vto_meter=2");
+              "+vto_meter=2 +no_defs");
 }
 
 // ---------------------------------------------------------------------------
@@ -7102,9 +7104,11 @@ TEST(io, projparse_longlat_axis_enu) {
                 std::string::npos)
         << wkt;
 
-    EXPECT_EQ(crs->exportToPROJString(PROJStringFormatter::create().get()),
-              "+proj=pipeline +step +proj=longlat +ellps=GRS80 +step "
-              "+proj=unitconvert +xy_in=rad +xy_out=deg");
+    auto op = CoordinateOperationFactory::create()->createOperation(
+        GeographicCRS::EPSG_4326, NN_NO_CHECK(crs));
+    ASSERT_TRUE(op != nullptr);
+    EXPECT_EQ(op->exportToPROJString(PROJStringFormatter::create().get()),
+              "+proj=axisswap +order=2,1");
 }
 
 // ---------------------------------------------------------------------------
@@ -7127,10 +7131,10 @@ TEST(io, projparse_longlat_axis_neu) {
                 std::string::npos)
         << wkt;
 
-    EXPECT_EQ(crs->exportToPROJString(PROJStringFormatter::create().get()),
-              "+proj=pipeline +step +proj=longlat +ellps=GRS80 +step "
-              "+proj=unitconvert +xy_in=rad +xy_out=deg +step +proj=axisswap "
-              "+order=2,1");
+    auto op = CoordinateOperationFactory::create()->createOperation(
+        GeographicCRS::EPSG_4326, NN_NO_CHECK(crs));
+    ASSERT_TRUE(op != nullptr);
+    EXPECT_EQ(op->exportToPROJString(PROJStringFormatter::create().get()), "");
 }
 
 // ---------------------------------------------------------------------------
@@ -7153,10 +7157,12 @@ TEST(io, projparse_longlat_axis_swu) {
                 std::string::npos)
         << wkt;
 
-    EXPECT_EQ(crs->exportToPROJString(PROJStringFormatter::create().get()),
-              "+proj=pipeline +step +proj=longlat +ellps=GRS80 +step "
-              "+proj=unitconvert +xy_in=rad +xy_out=deg +step +proj=axisswap "
-              "+order=-2,-1");
+    auto op = CoordinateOperationFactory::create()->createOperation(
+        GeographicCRS::EPSG_4326, NN_NO_CHECK(crs));
+    ASSERT_TRUE(op != nullptr);
+    EXPECT_EQ(op->exportToPROJString(PROJStringFormatter::create().get()),
+              "+proj=pipeline +step +proj=axisswap +order=2,1 +step "
+              "+proj=axisswap +order=-2,-1");
 }
 
 // ---------------------------------------------------------------------------
@@ -7168,9 +7174,11 @@ TEST(io, projparse_longlat_unitconvert_deg) {
     auto crs = nn_dynamic_pointer_cast<GeographicCRS>(obj);
     ASSERT_TRUE(crs != nullptr);
 
-    EXPECT_EQ(crs->exportToPROJString(PROJStringFormatter::create().get()),
-              "+proj=pipeline +step +proj=longlat +ellps=GRS80 +step "
-              "+proj=unitconvert +xy_in=rad +xy_out=deg");
+    auto op = CoordinateOperationFactory::create()->createOperation(
+        GeographicCRS::EPSG_4326, NN_NO_CHECK(crs));
+    ASSERT_TRUE(op != nullptr);
+    EXPECT_EQ(op->exportToPROJString(PROJStringFormatter::create().get()),
+              "+proj=axisswap +order=2,1");
 }
 
 // ---------------------------------------------------------------------------
@@ -7182,8 +7190,12 @@ TEST(io, projparse_longlat_unitconvert_grad) {
     auto crs = nn_dynamic_pointer_cast<GeographicCRS>(obj);
     ASSERT_TRUE(crs != nullptr);
 
-    EXPECT_EQ(crs->exportToPROJString(PROJStringFormatter::create().get()),
-              "+proj=pipeline +step +proj=longlat +ellps=GRS80 +step "
+    auto op = CoordinateOperationFactory::create()->createOperation(
+        GeographicCRS::EPSG_4326, NN_NO_CHECK(crs));
+    ASSERT_TRUE(op != nullptr);
+    EXPECT_EQ(op->exportToPROJString(PROJStringFormatter::create().get()),
+              "+proj=pipeline +step +proj=axisswap +order=2,1 +step "
+              "+proj=unitconvert +xy_in=deg +xy_out=rad +step "
               "+proj=unitconvert +xy_in=rad +xy_out=grad");
 }
 
@@ -7196,9 +7208,12 @@ TEST(io, projparse_longlat_unitconvert_rad) {
     auto crs = nn_dynamic_pointer_cast<GeographicCRS>(obj);
     ASSERT_TRUE(crs != nullptr);
 
-    EXPECT_EQ(crs->exportToPROJString(PROJStringFormatter::create().get()),
-              "+proj=pipeline +step +proj=longlat +ellps=GRS80 +step "
-              "+proj=unitconvert +xy_in=rad +xy_out=rad");
+    auto op = CoordinateOperationFactory::create()->createOperation(
+        GeographicCRS::EPSG_4326, NN_NO_CHECK(crs));
+    ASSERT_TRUE(op != nullptr);
+    EXPECT_EQ(op->exportToPROJString(PROJStringFormatter::create().get()),
+              "+proj=pipeline +step +proj=axisswap +order=2,1 +step "
+              "+proj=unitconvert +xy_in=deg +xy_out=rad");
 }
 
 // ---------------------------------------------------------------------------
@@ -7215,13 +7230,16 @@ TEST(io, projparse_longlat_axisswap) {
                 auto crs = nn_dynamic_pointer_cast<GeographicCRS>(obj);
                 ASSERT_TRUE(crs != nullptr);
 
+                auto op = CoordinateOperationFactory::create()->createOperation(
+                    GeographicCRS::EPSG_4326, NN_NO_CHECK(crs));
+                ASSERT_TRUE(op != nullptr);
                 EXPECT_EQ(
-                    crs->exportToPROJString(
-                        PROJStringFormatter::create().get()),
-                    "+proj=pipeline +step +proj=longlat +ellps=GRS80 +step "
-                    "+proj=unitconvert +xy_in=rad +xy_out=deg +step "
-                    "+proj=axisswap +order=" +
-                        std::string(order1) + "," + order2);
+                    op->exportToPROJString(PROJStringFormatter::create().get()),
+                    (atoi(order1) == 2 && atoi(order2) == 1)
+                        ? ""
+                        : "+proj=pipeline +step +proj=axisswap +order=2,1 "
+                          "+step +proj=axisswap +order=" +
+                              std::string(order1) + "," + order2);
             }
         }
     }
@@ -7870,11 +7888,14 @@ TEST(io, projparse_axisswap_unitconvert_longlat_proj) {
     auto obj = PROJStringParser().createFromPROJString(input);
     auto crs = nn_dynamic_pointer_cast<ProjectedCRS>(obj);
     ASSERT_TRUE(crs != nullptr);
-    EXPECT_EQ(
-        crs->exportToPROJString(
-            PROJStringFormatter::create(PROJStringFormatter::Convention::PROJ_5)
-                .get()),
-        input);
+    auto op = CoordinateOperationFactory::create()->createOperation(
+        GeographicCRS::EPSG_4326, NN_NO_CHECK(crs));
+    ASSERT_TRUE(op != nullptr);
+    EXPECT_EQ(op->exportToPROJString(PROJStringFormatter::create().get()),
+              "+proj=pipeline +step +proj=axisswap +order=2,1 +step "
+              "+proj=unitconvert +xy_in=deg +xy_out=rad +step +proj=lcc "
+              "+lat_1=49.5 +lat_0=49.5 +lon_0=0 +k_0=0.999877341 +x_0=600000 "
+              "+y_0=200000 +ellps=clrk80ign +pm=paris");
 }
 
 // ---------------------------------------------------------------------------
@@ -7887,11 +7908,14 @@ TEST(io, projparse_axisswap_unitconvert_proj_axisswap) {
     auto obj = PROJStringParser().createFromPROJString(input);
     auto crs = nn_dynamic_pointer_cast<ProjectedCRS>(obj);
     ASSERT_TRUE(crs != nullptr);
-    EXPECT_EQ(
-        crs->exportToPROJString(
-            PROJStringFormatter::create(PROJStringFormatter::Convention::PROJ_5)
-                .get()),
-        input);
+    auto op = CoordinateOperationFactory::create()->createOperation(
+        GeographicCRS::EPSG_4326, NN_NO_CHECK(crs));
+    ASSERT_TRUE(op != nullptr);
+    EXPECT_EQ(op->exportToPROJString(PROJStringFormatter::create().get()),
+              "+proj=pipeline +step +proj=axisswap +order=2,1 +step "
+              "+proj=unitconvert +xy_in=deg +xy_out=rad +step +proj=igh "
+              "+lon_0=0 +x_0=0 +y_0=0 +ellps=GRS80 +step +proj=axisswap "
+              "+order=2,1");
 }
 
 // ---------------------------------------------------------------------------
@@ -7905,11 +7929,14 @@ TEST(io, projparse_axisswap_unitconvert_proj_unitconvert) {
     auto obj = PROJStringParser().createFromPROJString(input);
     auto crs = nn_dynamic_pointer_cast<ProjectedCRS>(obj);
     ASSERT_TRUE(crs != nullptr);
-    EXPECT_EQ(
-        crs->exportToPROJString(
-            PROJStringFormatter::create(PROJStringFormatter::Convention::PROJ_5)
-                .get()),
-        input);
+    auto op = CoordinateOperationFactory::create()->createOperation(
+        GeographicCRS::EPSG_4326, NN_NO_CHECK(crs));
+    ASSERT_TRUE(op != nullptr);
+    EXPECT_EQ(op->exportToPROJString(PROJStringFormatter::create().get()),
+              "+proj=pipeline +step +proj=axisswap +order=2,1 +step "
+              "+proj=unitconvert +xy_in=deg +xy_out=rad +step +proj=igh "
+              "+lon_0=0 +x_0=0 +y_0=0 +ellps=GRS80 +step +proj=unitconvert "
+              "+xy_in=m +z_in=m +xy_out=ft +z_out=ft");
 }
 
 // ---------------------------------------------------------------------------
@@ -7923,11 +7950,15 @@ TEST(io, projparse_axisswap_unitconvert_proj_unitconvert_numeric_axisswap) {
     auto obj = PROJStringParser().createFromPROJString(input);
     auto crs = nn_dynamic_pointer_cast<ProjectedCRS>(obj);
     ASSERT_TRUE(crs != nullptr);
-    EXPECT_EQ(
-        crs->exportToPROJString(
-            PROJStringFormatter::create(PROJStringFormatter::Convention::PROJ_5)
-                .get()),
-        input);
+    auto op = CoordinateOperationFactory::create()->createOperation(
+        GeographicCRS::EPSG_4326, NN_NO_CHECK(crs));
+    ASSERT_TRUE(op != nullptr);
+    EXPECT_EQ(op->exportToPROJString(PROJStringFormatter::create().get()),
+              "+proj=pipeline +step +proj=axisswap +order=2,1 +step "
+              "+proj=unitconvert +xy_in=deg +xy_out=rad +step +proj=igh "
+              "+lon_0=0 +x_0=0 +y_0=0 +ellps=GRS80 +step +proj=unitconvert "
+              "+xy_in=m +z_in=m +xy_out=2.5 +z_out=2.5 +step +proj=axisswap "
+              "+order=-2,-1");
 }
 
 // ---------------------------------------------------------------------------
@@ -8059,20 +8090,9 @@ TEST(io, projparse_projected_unknown) {
         EXPECT_EQ(wkt, expected_wkt1);
     }
 
-    EXPECT_EQ(
-        crs->exportToPROJString(
-            PROJStringFormatter::create(PROJStringFormatter::Convention::PROJ_4)
-                .get()),
-        "+proj=mbt_s +unused_flag +lat_0=45 +lon_0=0 +k=1 +x_0=10 "
-        "+y_0=0 +datum=WGS84 +units=m +no_defs");
-
-    EXPECT_EQ(
-        crs->exportToPROJString(
-            PROJStringFormatter::create(PROJStringFormatter::Convention::PROJ_5)
-                .get()),
-        "+proj=pipeline +step +proj=unitconvert +xy_in=deg +xy_out=rad "
-        "+step +proj=mbt_s +unused_flag +lat_0=45 +lon_0=0 +k=1 "
-        "+x_0=10 +y_0=0 +ellps=WGS84");
+    EXPECT_EQ(crs->exportToPROJString(PROJStringFormatter::create().get()),
+              "+proj=mbt_s +unused_flag +lat_0=45 +lon_0=0 +k=1 +x_0=10 "
+              "+y_0=0 +datum=WGS84 +units=m +no_defs");
 
     {
         auto obj2 = WKTParser().createFromWKT(expected_wkt1);
@@ -8160,11 +8180,14 @@ TEST(io, projparse_cart_unit) {
     auto obj = PROJStringParser().createFromPROJString(input);
     auto crs = nn_dynamic_pointer_cast<GeodeticCRS>(obj);
     ASSERT_TRUE(crs != nullptr);
-    EXPECT_EQ(
-        crs->exportToPROJString(
-            PROJStringFormatter::create(PROJStringFormatter::Convention::PROJ_5)
-                .get()),
-        input);
+    auto op = CoordinateOperationFactory::create()->createOperation(
+        GeographicCRS::EPSG_4326, NN_NO_CHECK(crs));
+    ASSERT_TRUE(op != nullptr);
+    EXPECT_EQ(op->exportToPROJString(PROJStringFormatter::create().get()),
+              "+proj=pipeline +step +proj=axisswap +order=2,1 +step "
+              "+proj=unitconvert +xy_in=deg +xy_out=rad +step +proj=cart "
+              "+ellps=WGS84 +step +proj=unitconvert +xy_in=m +z_in=m "
+              "+xy_out=km +z_out=km");
 }
 
 // ---------------------------------------------------------------------------
@@ -8176,11 +8199,14 @@ TEST(io, projparse_cart_unit_numeric) {
     auto obj = PROJStringParser().createFromPROJString(input);
     auto crs = nn_dynamic_pointer_cast<GeodeticCRS>(obj);
     ASSERT_TRUE(crs != nullptr);
-    EXPECT_EQ(
-        crs->exportToPROJString(
-            PROJStringFormatter::create(PROJStringFormatter::Convention::PROJ_5)
-                .get()),
-        input);
+    auto op = CoordinateOperationFactory::create()->createOperation(
+        GeographicCRS::EPSG_4326, NN_NO_CHECK(crs));
+    ASSERT_TRUE(op != nullptr);
+    EXPECT_EQ(op->exportToPROJString(PROJStringFormatter::create().get()),
+              "+proj=pipeline +step +proj=axisswap +order=2,1 +step "
+              "+proj=unitconvert +xy_in=deg +xy_out=rad +step +proj=cart "
+              "+ellps=WGS84 +step +proj=unitconvert +xy_in=m +z_in=m "
+              "+xy_out=500 +z_out=500");
 }
 
 // ---------------------------------------------------------------------------
@@ -8237,11 +8263,15 @@ TEST(io, projparse_ob_tran_longlat) {
     auto obj = PROJStringParser().createFromPROJString(input);
     auto crs = nn_dynamic_pointer_cast<DerivedGeographicCRS>(obj);
     ASSERT_TRUE(crs != nullptr);
-    EXPECT_EQ(
-        crs->exportToPROJString(
-            PROJStringFormatter::create(PROJStringFormatter::Convention::PROJ_5)
-                .get()),
-        input);
+    auto op = CoordinateOperationFactory::create()->createOperation(
+        GeographicCRS::EPSG_4326, NN_NO_CHECK(crs));
+    ASSERT_TRUE(op != nullptr);
+    EXPECT_EQ(op->exportToPROJString(PROJStringFormatter::create().get()),
+              "+proj=pipeline +step +proj=axisswap +order=2,1 +step "
+              "+proj=unitconvert +xy_in=deg +xy_out=rad +step +proj=ob_tran "
+              "+o_proj=longlat +o_lat_p=52 +o_lon_p=-30 +lon_0=-25 "
+              "+ellps=WGS84 +step +proj=unitconvert +xy_in=rad +xy_out=deg "
+              "+step +proj=axisswap +order=2,1");
 }
 
 // ---------------------------------------------------------------------------
@@ -8651,8 +8681,7 @@ TEST(io, projparse_init) {
         auto crs = nn_dynamic_pointer_cast<GeographicCRS>(obj);
         ASSERT_TRUE(crs != nullptr);
         EXPECT_EQ(crs->exportToPROJString(PROJStringFormatter::create().get()),
-                  "+proj=pipeline +step +proj=longlat +ellps=GRS80 "
-                  "+step +proj=unitconvert +xy_in=rad +xy_out=deg");
+                  "+proj=longlat +ellps=GRS80 +no_defs");
     }
 }
 
diff --git a/test/unit/test_operation.cpp b/test/unit/test_operation.cpp
index 9b9273b5..379ef31a 100644
--- a/test/unit/test_operation.cpp
+++ b/test/unit/test_operation.cpp
@@ -1377,9 +1377,8 @@ TEST(operation, tmerc_south_oriented_export) {
     auto crs = nn_dynamic_pointer_cast<ProjectedCRS>(obj);
     ASSERT_TRUE(crs != nullptr);
     EXPECT_EQ(crs->exportToPROJString(PROJStringFormatter::create().get()),
-              "+proj=pipeline +step +proj=axisswap +order=2,1 +step "
-              "+proj=unitconvert +xy_in=deg +xy_out=rad +step +proj=tmerc "
-              "+axis=wsu +lat_0=0 +lon_0=29 +k=1 +x_0=0 +y_0=0 +ellps=WGS84");
+              "+proj=tmerc +axis=wsu +lat_0=0 +lon_0=29 +k=1 +x_0=0 +y_0=0 "
+              "+ellps=WGS84 +units=m +no_defs");
 }
 
 // ---------------------------------------------------------------------------
@@ -1630,8 +1629,8 @@ TEST(operation, bonne_export) {
     auto crs = nn_dynamic_pointer_cast<ProjectedCRS>(obj);
     ASSERT_TRUE(crs != nullptr);
     EXPECT_EQ(crs->exportToPROJString(PROJStringFormatter::create().get()),
-              "+proj=pipeline +step +proj=unitconvert +xy_in=deg +xy_out=rad "
-              "+step +proj=bonne +lat_1=1 +lon_0=2 +x_0=3 +y_0=4 +ellps=WGS84");
+              "+proj=bonne +lat_1=1 +lon_0=2 +x_0=3 +y_0=4 +ellps=WGS84 "
+              "+units=m +no_defs");
 }
 
 // ---------------------------------------------------------------------------
@@ -3016,12 +3015,6 @@ TEST(operation, webmerc_export) {
     EXPECT_EQ(conv->exportToPROJString(PROJStringFormatter::create().get()),
               "+proj=webmerc +lat_0=0 +lon_0=2 +x_0=3 +y_0=4");
 
-    EXPECT_THROW(
-        conv->exportToPROJString(
-            PROJStringFormatter::create(PROJStringFormatter::Convention::PROJ_4)
-                .get()),
-        FormattingException);
-
     EXPECT_EQ(conv->exportToWKT(WKTFormatter::create().get()),
               "CONVERSION[\"Popular Visualisation Pseudo Mercator\",\n"
               "    METHOD[\"Popular Visualisation Pseudo Mercator\",\n"
@@ -3072,20 +3065,17 @@ TEST(operation, webmerc_export) {
         "+x_0=3 +y_0=4 +k=1 +units=m "
         "+nadgrids=@null +wktext +no_defs\"]]");
 
-    EXPECT_EQ(
-        projCRS->exportToPROJString(
-            PROJStringFormatter::create(PROJStringFormatter::Convention::PROJ_5)
-                .get()),
-        "+proj=pipeline +step +proj=axisswap +order=2,1 +step "
-        "+proj=unitconvert +xy_in=deg +xy_out=rad +step +proj=webmerc "
-        "+lat_0=0 +lon_0=2 +x_0=3 +y_0=4 +ellps=WGS84");
+    auto op = CoordinateOperationFactory::create()->createOperation(
+        GeographicCRS::EPSG_4326, projCRS);
+    ASSERT_TRUE(op != nullptr);
+    EXPECT_EQ(op->exportToPROJString(PROJStringFormatter::create().get()),
+              "+proj=pipeline +step +proj=axisswap +order=2,1 +step "
+              "+proj=unitconvert +xy_in=deg +xy_out=rad +step +proj=webmerc "
+              "+lat_0=0 +lon_0=2 +x_0=3 +y_0=4 +ellps=WGS84");
 
-    EXPECT_EQ(
-        projCRS->exportToPROJString(
-            PROJStringFormatter::create(PROJStringFormatter::Convention::PROJ_4)
-                .get()),
-        "+proj=merc +a=6378137 +b=6378137 +lat_ts=0 +lon_0=2 +x_0=3 "
-        "+y_0=4 +k=1 +units=m +nadgrids=@null +wktext +no_defs");
+    EXPECT_EQ(projCRS->exportToPROJString(PROJStringFormatter::create().get()),
+              "+proj=merc +a=6378137 +b=6378137 +lat_ts=0 +lon_0=2 +x_0=3 "
+              "+y_0=4 +k=1 +units=m +nadgrids=@null +wktext +no_defs");
 }
 
 // ---------------------------------------------------------------------------
@@ -3183,17 +3173,8 @@ TEST(operation, webmerc_import_from_GDAL_wkt1_EPSG_3785_deprecated) {
     ASSERT_TRUE(crs != nullptr);
 
     EXPECT_EQ(crs->exportToPROJString(PROJStringFormatter::create().get()),
-              "+proj=pipeline +step +proj=axisswap +order=2,1 +step "
-              "+proj=unitconvert +xy_in=deg +xy_out=rad +step +proj=webmerc "
-              "+lat_0=0 +lon_0=0 +x_0=0 +y_0=0 "
-              "+ellps=WGS84");
-
-    EXPECT_EQ(
-        crs->exportToPROJString(
-            PROJStringFormatter::create(PROJStringFormatter::Convention::PROJ_4)
-                .get()),
-        "+proj=merc +a=6378137 +b=6378137 +lat_ts=0 +lon_0=0 +x_0=0 "
-        "+y_0=0 +k=1 +units=m +nadgrids=@null +wktext +no_defs");
+              "+proj=merc +a=6378137 +b=6378137 +lat_ts=0 +lon_0=0 +x_0=0 "
+              "+y_0=0 +k=1 +units=m +nadgrids=@null +wktext +no_defs");
 
     auto convGot = crs->derivingConversion();
 
@@ -3257,16 +3238,8 @@ TEST(operation, webmerc_import_from_WKT2_EPSG_3785_deprecated) {
     ASSERT_TRUE(crs != nullptr);
 
     EXPECT_EQ(crs->exportToPROJString(PROJStringFormatter::create().get()),
-              "+proj=pipeline +step +proj=axisswap +order=2,1 +step "
-              "+proj=unitconvert +xy_in=deg +xy_out=rad +step +proj=webmerc "
-              "+ellps=WGS84");
-
-    EXPECT_EQ(
-        crs->exportToPROJString(
-            PROJStringFormatter::create(PROJStringFormatter::Convention::PROJ_4)
-                .get()),
-        "+proj=merc +a=6378137 +b=6378137 +lat_ts=0 +lon_0=0 +x_0=0 "
-        "+y_0=0 +k=1 +units=m +nadgrids=@null +wktext +no_defs");
+              "+proj=merc +a=6378137 +b=6378137 +lat_ts=0 +lon_0=0 +x_0=0 "
+              "+y_0=0 +k=1 +units=m +nadgrids=@null +wktext +no_defs");
 
     EXPECT_EQ(
         crs->exportToWKT(
@@ -4105,12 +4078,9 @@ TEST(operation, eqearth_export) {
 TEST(operation, laborde_oblique_mercator) {
 
     // Content of EPSG:29701 "Tananarive (Paris) / Laborde Grid"
-    auto projString = "+proj=pipeline +step +proj=axisswap +order=2,1 +step "
-                      "+proj=unitconvert +xy_in=grad +xy_out=rad +step +inv "
-                      "+proj=longlat +ellps=intl +pm=paris +step +proj=labrd "
-                      "+lat_0=-18.9 +lon_0=44.1 +azi=18.9 +k=0.9995 "
-                      "+x_0=400000 +y_0=800000 +ellps=intl +pm=paris +step "
-                      "+proj=axisswap +order=2,1";
+    auto projString = "+proj=labrd +lat_0=-18.9 +lon_0=44.1 +azi=18.9 "
+                      "+k=0.9995 +x_0=400000 +y_0=800000 +ellps=intl +pm=paris "
+                      "+units=m +no_defs";
     auto obj = PROJStringParser().createFromPROJString(projString);
     auto crs = nn_dynamic_pointer_cast<ProjectedCRS>(obj);
     ASSERT_TRUE(crs != nullptr);