General assignment is an FBI term for duties other than assignments such as the X-files.

In October 1993, Agent Jerry Lamana appealed to Special Agent Fox Mulder for assistance with a baffling murder case. Despite admitting that he would like to help Agent Lamana, Mulder implied that he couldn't, on the grounds that neither he nor his partner, Special Agent Dana Scully, were on general assignment due to having been assigned to the X-files. After Agent Lamana begged Mulder to help - mentioning that the victim, Benjamin Drake, was a good friend of the Attorney General's - both Mulder and Scully assisted with the case, ultimately finding that the case was a nonofficial X-file, pertaining to Artificial Intelligence. (TXF: "Ghost in the Machine")

It can likely be safely assumed that Mulder was on general assignment during his time off the X-files in 1994.