A string of one or more tempo changes programmed into a sequencing device that occur at specific points in a piece relating to the passage of some type time code, usually SMPTE or MTC. These forms of time code simply increment like a digital clock. There is no relationship to anything musical. So, when synchronizing a sequencer to this type of equipment it is necessary to enter the tempo changes and relate them to specific points in the passage of this time code so they will automatically happen at the right time in the piece. This is distinct from when you are working with MIDI clock, where the clock itself is running at a rate that indicates the tempo. Most modern production equipment doesn’t use MIDI clock for synchronization and is time code based instead; thus it is necessary to use tempo maps (as well as start times) in the sequence. Most modern sequencers that are designed for this type of production make this part of their operation relatively transparent to the end user.