INT 21 - PC/TCP IPCUST.SYS - RESET CONFIGURATION DATA READ POINTER
AX = 4403h
BX = file handle referencing device "$IPCUST"
CX, DS:DX ignored
Return: CF clear if successful
AX destroyed
CF set on error
AX = error code (01h,05h,06h,0Dh) (see AH=59h)
Note:   there are a total of 378h bytes of configuration data for IPCUST.SYS
version 2.05.  If less than the entire data is read or written,
the next read/write continues where the previous one ended; this
call and AX=4402h both reset the location at which the next
operation starts to zero
SeeAlso: AH=40h"IPCUST",AX=4402h"IPCUST"

See also: 213F

214403 - PC/TCP IPCUST.SYS - RESET CONFIGURATION DATA READ POINTER