idlwave-shell-file-name-chars

idlwave-shell-file-name-chars is a variable defined in `idlw-shell.el'.
Its value is

"~/A-Za-z0-9+:_.$#%={}\\- "

Documentation:
The characters allowed in file names, as a string.
Used for file name completion. Must not contain `'', `,' and `"'
because these are used as separators by IDL.

You can customize this variable.