Guiding principles
I feel like I might be misunderstanding our meeting about this. If all the guidelines are saying do not use special characters, why are we saying you can?
Ok, I was getting confused by what we are trying to say so I looked it up and I think we could adapt this example from https://instr.iastate.libguides.com/datashare/filenames
Avoid special characters Just because you can use something doesn't mean you should. There are two reasons to avoid special characters, punctuation marks, and symbols in filenames:
Special characters and punctuation marks are often reserved characters for computer operating systems. This means that the character is used in a very specififc way by the operating system and using it in a file name will cause errors. Not all operating systems and programs support the same characters. A common example is how the modern Mac OS (9 and after) support a number of special characters (/ \ : * ? < > |) that are not supported by Windows. Also: Never Use Emojis in file names! It's a very bad idea at this time.
They also have a good reference https://blog.josephscott.org/2007/02/12/things-that-shouldnt-be-in-file-names-for-1000-alex/