When looking at the discrete LEDs from Visual Communications Company - VCC such as CMD15-21VRD-TR8 the “TR8” is calling out that the parts come on a tape and reel from the manufacturer.
Applicable part numbers
CMD15-21VGD/TR8 CMD17-21VGC/TR8 CMD17-21VRC/TR8 CMD15-21VRD/TR8 CMD17-21VGD/TR8 CMD15-21VGC/TR8 CMD17-21VRD/TR8 CMD28-21VGC/TR8 CMD15-21UGC/TR8 CMD28-21VRC/TR8 CMD15-21SRC/TR8 CMD17-21SRC/TR8 CMD15-21UBC/TR8 CMD17-21VYC/TR8 CMD15-21VYD/TR8 CMD15-21VRC/TR8 CMD17-21UGC/TR8 CMD11-21VRC/TR8 CMD11-21VGC/TR8 CMD17-21VYD/TR8 CMD12-21VGC/TR8 CMD67-21VGC/TR8 CMD12-21SRC/TR8 CMD1522SRUGCTR8 CMD6722SRUGCTR8 CMD11-21VYC/TR8 CMD12-21VYC/TR8 CMD67-21VRC/TR8 CMD67-21URC/TR8 CMD9322SRVGCTR8 CMD11-21SRC/TR8 CMD6722VRVGCTR8 CMD2821VRCTR8T1 CMD2821VYCTR8T1 CMD67-21VYC/TR8 CMD12-21UGC/TR8 CMD12-21VRC/TR8 CMD15-21VYC/TR8 CMD1522VRVGCTR8 CMD67-21SRC/TR8 CMD67-21UWC/TR8 CMD2821SDRC/TR8 CMD11-21UBC/TR8 CMD15-22VRVGC/TR8 CMD28-21VYC/TR8 CMD28-21SRC/TR8 CMD28-21VYC/TR8/T1 CMD2821VGCTR8T1 CMD28-21SRC/TR8/T1 CMD93-21VGC/TR8 CMD93-21VYC/TR8 CMD93-21VRC/TR8 CMD93-21SRC/TR8 CMD17-21UYC/TR8 CMD12-21SOC/TR8 CMD67-21UBC/TR8 CMD1122SRVGCTR8 CMD17-21UBC/TR8