I'm not sure this is proper usage. Virgule is French for Comma, not Slash. And to my knowledge, there is no French equivalent for Slash and if there is, it's not commonly used.
> I wasn't speaking French, I was speaking English, in which virgule means slash.
It seems like you and GP both have valid points.
Borrow-words usually (AFAIK) generally have the same meaning in the donor and recipient languages. So referring to the donor-language definition is a good way to figure out intended usage.
IIUC, virgule has different meanings in Latin, French, and English. I'm guessing that's what's throwing us off.
