It might not be a file called OM.lsp.  If it were me, I would probably call the file something like OffsetMultiple.lsp, so I'd know what it was about when looking at file names, with the command name defined inside it as OM for short.  But even that would only apply if it's defined in a file devoted to only the one command.  It might rather be in the acaddoc.lsp file, or some other .lsp file that contains definitions of multiple commands -- looking at the APPLOAD history will show the file name, but not the names of commands defined within it.

 

What you really should try to find is a file containing C:OM in it, because if it's an AutoLISP-(defun)'d command, that will necessarily be the command-name designation.  The basic Windows Explorer Search function won't search for content within .lsp files as it will in .txt or .doc or some other file types, but there may be a way to add that file type to those that it will search within, or other means of searching for content inside files.

 

Then there's also the possibility that it's in some kind of compiled file format, such as .arx or .fas, that may not be searchable in that way at all (I haven't tried such a thing).

 

Thanks