actually I didn't understood what do You want. You can change file name extension if You like. You can call any file for execution on OSP. File name extention is only for convenience. Operating system will warn, if file content is wrong.
Am I speaking about subject?
If You want to have directory ("list" in some other, not Okuma operating systems), You need to command output to file or RS232 port instead of default output device - TT (terminal). But "list" has another meaning on Okuma OSP, hence I'm lost what You are asking about. LST is not a part of file name, as I remember. It's a command of Okuma OSP. Is that right?
but this is becoming a burden
if You can be more specific, what is becoming a burden?