What file names are not allowed in OneDrive?

Microsoft has an article on the topic here. Some highlights:

• " * : < > ? / \ | characters are not allowed. For some older versions, ~ # % & { }. are also not allowed. (The period in that latter list seems a little alarming!) Less citeable support channels report that dollar signs $ should also be avoided in file names.

• _vti_ cannot appear anywhere in a file name

• forms isn't supported as a file name when the folder is at the root level for a library, and sometimes when it is not at the root level for a library. (How was that supposed to be obvious?)

• You can’t create a folder name in SharePoint Online that begins with a tilde (~) or have any filename starting with ~$.

• The following names are prohibited: .lock, CON, PRN, AUX, NUL, COM1 - COM9, LPT1 - LPT9, desktop.ini.

• Active Outlook .PST files should NOT be synced in OneDrive.

• Symbolic links, junction points, authenticated proxies, and network/mapped drives are not allowed.

• OneNote notebooks initially created outside of OneDrive cannot be moved into OneDrive.

Forms appears to be one of the "illegal" words. I renamed it to Forms 2 and everything would sync. Rename it back to Forms and red Xs everywhere. I'm also looking for this magical list that will tell us what words aren't allowed. Why would forms not be a valid name?