Format of DOS 4.0+ data segment subsegment control blocks:
Offset Size Description )
00h BYTE subsegment type (blocks typically appear in this order)
"D" device driver
"E" device driver appendage
"I" IFS (Installable File System) driver
(MS-DOS 7) high-loaded drive data table array (see #02603)
"F" FILES= control block storage area (for FILES>5)
"X" FCBS= control block storage area, if present
"C" BUFFERS EMS workspace area (if BUFFERS /X option used)
"B" BUFFERS= storage area
"L" LASTDRIVE= current directory structure array storage area
"S" STACKS= code and data area, if present (see #01634,#01635)
"T" INSTALL= transient code
01h WORD paragraph of subsegment start (usually the next paragraph)
03h WORD size of subsegment in paragraphs
05h 3 BYTEs unused
08h 8 BYTEs for types "D" and "I", base name of file from which the driver
was loaded (unused for other types)