I figured that adding the -diff option meant that it ignored the "Read Only" flag. What it actually does is get the union of 2 sets of files 1) those files that have their "Read Only" flag unset AND 2) those files that have been modified ("Read Only" flag can remain set)
$ tfpt online "D:\a\b\c.txt" -diff -preview
Getting your pending changes from the server...
Checking the status of D:\a\b\c.txt... Done
Walking D:\a\b\c.txt... Found 1
Showing potential changes only. No changes made.
Edits:
edit: D:\a\b\c.txt
Showing potential changes only. No changes made.
$ tf diff "D:\a\b\c.txt"
Comparing local to latest: D:\a\b\c.txt
$
What I'd really like is for tfpt online to ignore the "Read Only" flag and ONLY list files that have actually been modified. Is this possible?