There isn't a direct function in Lotus Script to check if files exist.
Most of us have written a function like this multiple times as a helper.
I am working on an application which will be available as open source soon and I needed one again...
Here is a version of a check function, which should cover all cases and might be useful for you too.
It doesn't handle hidden files -- I know. But I didn't want to add that logic.
This is a companion discussion topic for the original entry at https://blog.nashcom.de/nashcomblog.nsf/dx/lotus-script-check-if-a-file-or-folder-exists.htm