fix two typos

1 files changed, 1 insertions, 1 deletions

diff --git a/grid_tools/README.md b/grid_tools/README.md
index f8cab3c..b717373 100644
--- a/grid_tools/README.md
+++ b/grid_tools/README.md
@@ -47,7 +47,7 @@ Options:
 * --do-not-write-accuracy-samples: To prevent accuracy samples from the NTv2 grid to be written in the output. Note: if it is detected that those samples are set to dummy values (negative values), they will automatically be discarded
 * --positive-longitude-shift-value {east,west}: To force the convention for the longitude shift value. NTv2 uses a positive-is-west convention, that is confusing. By default, the script will negate the sign of the longitude shift values to output a positive-is-east convention. Setting this option to "west" will preserve the original convention. Not recommended
 * --uint16-encoding: Whether values should be encoded on a 16-bit unsigned value, using a offset and scale floating point values. Default behaviour is to use Float32 encoding, which will preserve the binary values of the original NTv2 file
-* --datetime DATETIME: to specify the value of the TIFF DateTime tag. Must be formatted as "YYYY:MM:DD HH:MM:SS" (note the use of column as the separator for the Y-M-D part, as mandated by the TIFF specification). If not specified, the script will try to use the value from the corresponding NTv2 header
+* --datetime DATETIME: to specify the value of the TIFF DateTime tag. Must be formatted as "YYYY:MM:DD HH:MM:SS" (note the use of colon as the separator for the Y-M-D part, as mandated by the TIFF specification). If not specified, the script will try to use the value from the corresponding NTv2 header
 * --accuracy-unit {arc-second,metre,unknown}: to specify the unit of the accuracy samples. The NTv2 specification has been [historically interpreted in different ways regarding that](https://github.com/OSGeo/PROJ/wiki/Units-of-NTv2-accuracy-samples-%3F). Mandatory if accuracy samples are written (the script contains a few hardcoded rules for known datasets)
 
 Example: