Pitch and Position Count — Footprint Fit for Standard MTA-100 Receptacles
The 644180-1: 13 positions are molded, but only 12 are loaded with pins. The unloaded position can serve as a keying feature or be left open for future circuit expansion — it is not a missing contact.
Locking and Shrouding — Friction Lock for Quick Assembly
The single-wall shroud provides basic polarization and protects the pins during handling, but does not fully enclose them — board layout should allow clearance for the receptacle body.