>>-+--------+--$EXTP--type-code--,DCT--=--+-dct-addrx-+--------->
   '-symbol-'                             '-(--Rn--)--'   

>--+-------------------------+---------------------------------><
   '-,PARM--=--+-loc-addrx-+-'   
               '-(--R0--)--'     

type

Specifies the type of operation as follows:

OPEN

Initiate processing

GET

Receive one record

PUT

Send one record

CLOSE

Terminate processing

NCLOSE

Abnormally terminate processing

READ

Receive one NJE record

WRITE

Send one NJE record

DCT=

Specifies either a pointer to a DCT or the address of a DCT that represents the remote terminal device; if a read or write, it represents a line DCT. If dct is written as an address, it represents the address of a fullword, which in its three rightmost bytes contains the address of the remote terminal device DCT. This word must be located on a word boundary in storage. If dct is written using register notation (either regular or special register notation), it represents the address of the remote terminal device DCT.

PARM=

If type specifies either OPEN, CLOSE, NCLOSE, READ, or WRITE, this parameter should not be specified. If type specifies GET, this parameter specifies the address of an area into which the input record will be placed. The input area must be defined large enough to contain the largest record to be received.

If the type-code is specified as PUT, this keyword specifies the address of a parameter area containing a CCW command code which contains the carriage control (or stacker select), the data length, and the starting address of the data in the following format:

AL1

CCW command word

AL3

Data length

AL4

Starting address

If register notation is used, the appropriate address must be loaded into the designated register before the execution of this macro instruction. The data area being PUT must have 3 bytes in front of the supplied address that can be overwritten.

On return, the condition code is set as follows:

When type is OPEN,PUT,CLOSE,NCLOSE,READ,WRITE

CC>0

Successful completion

CC=0

Unsuccessful completion

When type is GET

CC>0

Successful GET processing

CC=0

Unsuccessful GET processing

CC<0

End-of-file received

• Main task.
• $WAIT can occur.