Time-patterns may be entered with a MIDI instrument. Bring to front either the "Grammar" or "Alphabet" window and select "Load time-pattern" in the "File" menu. The rest is self-explanatory: BP2 captures notes played on the MIDI input and stores their relative durations.

Note that it is necessary to play an extra note at the end because durations are measured on the basis of NoteOn messages. NoteOff's are ignored. It is therefore evident that n notes define n-1 time intervals.

Each time-pattern may be assigned a variable. BP2 suggests labels "Tp1", "Tp2", etc. and inserts automatically a rule rewriting "Tp..." as the sequence of durations entered.

Notes used for defining time-patterns must be played in sequence: playing chords would mess durations because simultaneous events actually do not produce simultaneous MIDI codes. You may for instance play the Mozart piece "with one finger" (plus the extra note at the end) and store the 96 beats obtained as "Tp1". All variations will then be played exactly with the same expressive (or dull) duration ratios. You may also play parts of the piece several times and store them as optional time-patterns randomly selected by the grammar. With context-sensitive or programmed grammars (see §11) musically significant effects could be obtained.