this predicate returns true if the program is runing in fastforward mode, e.g., as in the initial phase of a antescofo::starfrom... or antescofo::playfrom... commands. See paragraph Controlling the Execution Flow.

This predicate can be used to avoid or to perform a specific computation in this mode.

The fastforward mode is used to reach a location in the score where the normal execution resumes. In fastforward mode, all computation are done, except the final sending of messages, which is inhibited. In addition, if the keyword antescofo_is_in_rehearsal_mode appears in the score, the local actions are not triggered.

In fastforward mode, the time is spent in virtual time, meaning that the clock goes as fast as possible. See Transport, tempo computation, and others practicalities

See also @is_fastforward, @is_following_on, @is_paused, @is_playing_on, @is_running, and @is_stopped.