I used to work in a big legal firm with loads of lawyers, auditors etc and often after their names there was this type of indication. It meant which building they were to be found in and what was their office number.

perhaps it applies here ? depends on the size of the firm ......

This really should have been said under David's comment, but after the third failed attempt, I'm using this instead. But do give David the Kudoz ;-)

I agree with David's suggestion; my sister-in-law is a lawyer and I have often been meeting her up at the tribunal she is attached to when going to lunch with her. It's a fairly big tribunal covering a wide area of villages and towns, so that lawyers often do not know one another by name before some quite time. It's therefore very frequent to hear one asking for a letter or document to be passed on to another one perhaps just standing two feet away, with the reception personal replying "maitre XXX .... P23" or whatever similar. This being the number and location of the given lawyer's mailbox at the tribunal.