You must specify an operation code for each machine instruction statement. The symbolic operation code, or mnemonic code as it is also called, indicates the type of operation to be done; for example, A indicates the addition operation. Refer to the z/Architecture Principles of Operation information for a complete list of symbolic operation codes and the formats of the corresponding machine instructions.

Operation code format

>>-VERB--+----------+--+-----------+--+----------------+-------><
         '-MODIFIER-'  '-DATA TYPE-'  '-MACHINE FORMAT-'   

Verb

The verb must always be present. It typically consists of one or two characters and specifies the operation to be done. The verb is underscored in the following examples:

         A    3,AREA         A indicates an add operation
         MVC  TO,FROM        MV indicates a move operation

The other items in the operation code are not always present. They include the following (underscores are used to indicate modifiers, data types, and machine formats in the following examples):

Modifier

Modifier, which further defines the operation:

         AL  3,AREA          L indicates a logical operation

Data Type

Type qualifier, which indicates the type of data used by the instruction in its operation:

         CVB 3,BINAREA       B indicates binary data

         MVC TO,FROM         C indicates character data

         AE  2,FLTSHRT       E indicates normalized short
                             floating-point data

         AD  2,FLTLONG       D indicates normalized long
                             floating-point data

Machine Format

Format qualifier, R indicating a register operand, or I indicating an immediate operand. For example:

         ADR 2,4             R indicates a register operand

         MVI FIELD,X'A1'     I indicates an immediate operand
         AHI 7,123