DEF
Beginner
A computer file that records where everything has been put on the chip.
Novice
Design Exchange Format: a text file that records a design’s physical state: the chip outline, the rows, where each part sits and which way it faces, the pins, the blocked areas and, later, every wire.
Expert
Each component carries a placement status: FIXED (automatic tools may not move it), PLACED (they may), COVER (part of a cover macro; nothing may move it) or UNPLACED. A floorplan DEF is the hand-off to placement or physical synthesis, so its units, site names and orientations must match the LEF.