LQ(L-NL-NIO-1) IOcb/NOFF IOcb: I/O control byte (16 bits) NOFF = NIO + NL + 12 (16 bits) LQ(L-NL-NIO) IOW (1) first extra I/O descriptor word (if any) ... LQ(L-NL-1) IOW (NIO) last extra I/O descriptor word LQ(L-NL) link NL last reference link ... LQ(L-NS-1) link NS+1 first reference link LQ(L-NS) link NS last structural link ... LQ(L-1) link 1 first structural link LQ(L) next adr of the next bank in the linear str. LQ(L+1) up adr of the supporting bank LQ(L+2) origin adr of the supporting link IQ(L-5) IDN numeric bank ID IQ(L-4) IDH Hollerith bank ID (4 characters) IQ(L-3) NL number of links IQ(L-2) NS number of structural links IQ(L-1) ND number of data words IQ(L) status bits 1-18 user 19-32 system 25: drop bit 19-22 NIO 26: mark bit IQ(L+1) first data word ... IQ(L+ND) last data word This layout requires: DIMENSION LQ(999), IQ(999), Q(999) EQUIVALENCE (LQ(9),IQ(1),Q(1)) ---- Format of a short dead region ---- word 1: bits 1-16: NW, # of words, with 0 < NW < 12 17-24: NW again for redundancy 25: drop-bit set 26-end: zero 2->NW: dead words, content irrelevant