https://www.photools.com/help/imatch/var_basics.htm?dl=h-240 (https://www.photools.com/help/imatch/var_basics.htm?dl=h-240)
The third example says:
{File.MD.XMP::dc\description\Description\0:substr(0,50}
But I think it should be somethink like:
{File.MD.XMP::dc\description\Description\0|substr:0,50}
Thanks. Fixed for the 2023 help edition.