The Tektronix DF2 is a display formatter for use with the 7D01 logic analyzer. It is a DF1 with special support for debugging GPIB. The DF2 does not, however, have a GPIB interface of its own - it can only analyze it. This functionality is invoked with the added MENU control (refer to the instruction manual for details).
A 103-0209-00 GPIB to probe comb adapter was supplied with the DF2.