(*) Those who have worked with SQL Server for a long time, know that once there was something called "global variables", and indeed they had leading @@. But they were all pre-defined and readonly, that is @@spid, @procid and the like. Today they are referred to as functions, but you can still use them in context where normal built-in functions cannot be used.
Do you mean Sybase? I have worked with SQL server since their rebranded version of Sybase. Some people might called them as they used to in Sybase, but I cannot remember that these ones were ever refered to as "global variables" in MS SQL specs. Well, I could be very wrong, as it was really long-long ago, when I couldn't read in English :-D.