Allows placing a specific unit (A=1, B=2, C=3, …) of a multi-unit KiCad
symbol rather than always defaulting to unit 1. Required for quad
optocouplers, dual op-amps, and other multi-unit parts where each channel
must be placed independently.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>