SCA also stands for Single Connector Attachment, an 80-pin SCSI device interconnection standard. SCA defines all pins required by the SCSI-3 Parallel Interface proposed standard. The same connector carries all required power, ground, and auxiliary signals (such as spindle synch, I/D select, and motor start control). It is typically used as a standard for drives plugging directly into a backplane. It can be (and often is) used in hot-pluggable situations. For pinouts, mechanical definitions, and further (more definitive) information, see http://playground.sun.com/pub/SCA/SCAR3-2.txt.