Notes

For more information about manipulating bits in bit lists, see FD_ZERO, FD_CLR, FD_SET, and FD_ISSET #SOCKET function.
For programming languages like COBOL and CA ADS where it is difficult to manipulate bits in bit lists, byte lists can be used by specifying a SOCKET-SELECT-BYTELIST for option. In this case, the read-list, write-list, and exception-list are byte lists instead of bit lists. In byte lists, each byte represents one socket descriptor. A socket descriptor will be processed if its corresponding byte is set to the character '1'. A socket descriptor's corresponding byte is the nth byte relative to 1 in the list, where n is equal to the value of socket descriptor + 1.
ECB and ECBLIST are mutually exclusive parameters.
z/VM systems: If multiple TCP/IP stacks are used, all the sockets represented by a bit in the 3 bit lists must be created in the same TCP/IP stack.
z/VSE systems: The SELECT and SELECTX functions are not supported.
The following table lists the options that can be specified. The EQUate symbol is generated by the #SOCKET TCPIPDEF macro call and the field names are associated with the SOCKET-MISC-DEFINITIONS.

EQUate Symbol	Field Name	Description
SEL@BBKW	SOCKET-SELECT-BITBACKWARD	Specifies that the bits in the fullwords are in the backward order. This is the default value if the parameter is assigned to NULL.
SEL@BFRW	SOCKET-SELECT-BITFORWARD	Specifies that the bits in each fullword are in the forward order
SEL@BYTV	SOCKET-SELECT-BYTELIST	Specifies that the read-list, write-list, and exception-list are byte lists instead of bit lists.

PL/I programs: The SOCKET_MISC_DEFINITIONS is used and the dashes are replaced by underscores.