I did a quick recheck after last commit setting up NFILEN to 256

• em crashes when called with filename argument longer than 255 [easy to fix with mystrscpy instead of strcpy]

• as em variables size are limited to 127+1, longer filenames will create problems with macroes [ex: $cfname holds the filename of current buffer]

• write-file command can be called with strings up to and longer than 255, so em will create files having up to 255 characters, but can't open them either with find-file command or as argument from command line [LOCK ERROR: cannot access lock file - File name too long]

• filenames completion works, a manual display refresh [^L] is necessary to clean up the display.

attached is a simple em script I used to generate the files for test: [strip .txt extension]
tstfnam.cmd.txt

I would suggest to limit NFILEN to 128 for now and fix the strcpy of filename arg issue.