So, in the arena of stupid programmers, it turns out "/" is forbidden.
The only problem is - not forbidden enough.
The end user can save a document with "/" in the name, but it will not end well.
MS Office thinks the file is read only if "/" is in the name. (Older Office 2011 - OS X Versions)
If you are getting a read only attribute set on documents in
Microsoft Office on OS X, check the file name.
Not the file attributes from the file system, but the properties from the file menu in the
application (Excel in this case).
The document was being used for a mail merge and it gave an error:
Word was unable to open the data source
So, some fine programming going on there.
Until they figure out a way to parse things, I suggest using "-" in your file names with dates in them.
Never a dull moment with stellar products like this around.
In looking around, I see that the filesystem HFS is not blameless either -
it looks like they substitue ":" for "/".
I am thinking the file system should disallow it if it denotes a path, and not lead the user on.