ARCTVEXT Parameter List

Table 1 shows that register 1 contains the address of the ARCTVEXT parameter list.

Note: If there is an alternate volume, there are three addresses in the parameter list; if there is no alternate volume, there are only two addresses in the parameter list. The high order bit of the second address distinguishes between these two options.

Table 1. ARCTVEXT Parameter List
Offset	Length or Bit Pattern	Description
0 (X'00')	4	The address of an 8-byte area (see Table 1), where the first 6 bytes contain the volume serial number of the volume having no valid data, followed by a 2-byte field.
4 (X'04')	4	The address of a fullword binary return code described in ARCTVEXT Return Codes. If the high order bit is 1, then there is no alternate volume and the parameter list is 8 bytes long. If the high order bit is 0 and the address at offset 8 is nonzero, then there is an alternate volume and the parameter list is 12 bytes long.
8 (X'08')	4	The address of an 8-byte area (see Table 1), where the first 6 bytes contain the volume serial number of the alternate volume that has no valid data, followed by a 2-byte field.