Akai DD1500 User Manual page 119

EDITING - 14
You may also insert referenced to the source material's SYNC mark. This is useful for
bringing in material that needs to synchronise to specific visual events or to another piece
of audio (a clichéd example would be to sync a music crescendo to a gun shot).
Pressing INSERT, SYNC, EXECUTE would give this result:
NOW
BEFORE INSERT
AFTER INSERT + SYNC
NOTE: If you try to insert referenced to a SYNC mark and there isn't one, it will insert
referenced to the source material's IN point
In both examples, you may also use the clipboards 1-9. For example, INSERT, OUT, 6,
EXECUTE would insert clipboard 6 referenced to its OUT point.
Version 2.00 - March, 1996 Page 111