Operand entries

Specify one or more operands in each machine instruction statement to provide the data or the location of the data upon which the machine operation is to be done. The operand entries consist of one or more fields or subfields, depending on the format of the instruction being coded. They can specify a register, an address, a length, or immediate data. You can omit length fields or subfields, which the assembler computes for you from the other operand entries. You can code an operand entry either with symbols or with self-defining terms.

The rules for coding operand entries are:

A comma must separate operands.
Parentheses must enclose subfields.
A comma must separate subfields enclosed in parentheses.
If a subfield is omitted because it is implicit in a symbolic address, the parentheses that enclosed the subfield must be omitted.
If two subfields are enclosed in parentheses and separated by commas, the following applies:
- If both subfields are omitted because they are implicit in a symbolic entry, the separating comma and the parentheses that were needed must also be omitted.
- If the first subfield is omitted, the comma that separates it from the second subfield must be written, as well as the enclosing parentheses.
- If the second subfield is omitted, the comma that separates it from the first subfield must be omitted; however, the enclosing parentheses must be written.
Spaces must not appear within the operand field, except as part of a character self-defining term, or in the specification of a character literal.