Hi bazography,
One way you could approach this is to make Your codes have "OM-1" in them and them and then insert the {model} variable into the full code replacement string.
Example code replacement line:
OM-1_foo New text
Then use this in a PM field:
={model}_foo=
For any files from the OM-1, that will replace to "New text" and for other cameras, the "default replacement" would be inserted. You could set this up with all the models you use for different replacements based on the camera model.
Depending on the situation, though, it might be cleaner to use Hot Codes, which allow for empty default replacements so that for non-OM-1 cameras, nothing would be inserted
The Code Replacement file for that might look something like this (I will attach the .tsv, too):
// Code Replacement file with Hot Codes for Photo Mechanic
//== {model}
//## foo
OM-1 New text
//??
If you use [foo] in any metadata field (note the square brackets for hot codes,) then on all files from an OM-1, "New text" would get inserted and for all other cameras, nothing would get inserted. The line that starts //?? is where you would put default replacements. Not putting anything there means that when PM encounters [foo] from a model other than OM-1 it will not insert anything
Hopefully, you can start playing around with these ideas and adapt them to fit your desired outcomes :-)
-Mick
More documentation:
Deep dive into Hot Codes:
https://docs.camerabits.com/support/solutions/articles/48000358684-hot-codesVideo webinar about Hot Codes:
https://www.youtube.com/watch?v=v_y7agK6X_8