I am a prospective user. I want to rename in the format constant_YYMMDD_9999 where 9999 is the 4 digit number from the original filename from the camera. Is this possible in Photo Mechanic?
In general, yes. If your camera writes out the frame number inside the image then you can use the {frame} variable for the last part at any time. Otherwise if your images still have their original names, you can extract the last four characters of the filename and use that. So here are two ways you could do that renaming:
constant_{year2}{month0}{day0}_{frame}
constant_{year2}{month0}{day0}_{filenamebase:-4}
HTH,
-Kirk