PL-L stands for plug-in lamps in the long version.
The PL-S stands for plug-in lamps in the short version.
PL-T stands for plug-in lamp with three compact fluorescent (3U).
PL-C stands for lamp plug-in cluster fluorescent cluster.
PL-R stands for plug-in radius lamp model (long socket).
PL-H stands for high output plug-in lights.
PL-Q stands for Quadrant (2D) flat lights.