Hi

How can I export a prj file and its catalog in inches to metric inch measurements?

thanks for your help

You can't, however if you set the config file to metric/inch measurement, you will be able to load and use the full imperial spec with this unit system.

You don't necessarily want to be doing that. For example ANSI component dimensions are slightly different between the SI/metric and imperial values due to conversion and significant figure/rounding practices.

I'd recommend having two separate global catalogs - one metric, one imperial.