Coding the macro instructions

The following paragraphs describe the notation used to define the macro syntax in this publication.

The set of symbols listed below are used to define macro instructions, but should never be written in the actual macro instruction:
hyphen

-

underscore

_

braces

{ }

brackets

[ ]

ellipsis

. . .

The special uses of these symbols are explained in paragraphs 4-8.
Uppercase letters and words, numbers, and the set of symbols listed below should be written in macro instructions exactly as shown in the definition:
apostrophe

'

asterisk

*

comma

,

equal sign

=

parentheses

( )

period

.
Lowercase letters, words, and symbols appearing in a macro instruction definition represent variables for which specific information should be substituted in the actual macro instruction.
Example: If name appears in a macro instruction definition, a specific value (for example, ALPHA) should be substituted for the variable in the actual macro instruction.
Hyphens join lowercase letters, words, and symbols to form a single variable.
Example: If member-name appears in a macro instruction definition, a specific value (for example, BETA) should be substituted for the variable in the actual macro instruction.
An underscore indicates a default option. If an underscored alternative is selected, it need not be written in the actual macro instruction.
Example: The representation
```
A     {A}
B  or {B}
C     {C}
```
indicates that either A or B or C should be selected; however, if B is selected, it need not be written because it is the default option.
Braces group related items, such as alternatives.
Example: The representation
```
       {A}
ALPHA=({B},D)
       {C}
```
indicates that a choice should be made among the items enclosed within the braces. If A is selected, the result is ALPHA=(A,D). If B is selected, the result can be either ALPHA=(,D) or ALPHA=(B,D).
Brackets also group related items; however, everything within the brackets is optional and may be omitted.
Example: The representation
```
       [A]
ALPHA=([B],D)
       [C]
```
indicates that a choice can be made among the items enclosed within the brackets or that the items within the brackets can be omitted. If B is selected, the result is: ALPHA=(B,D). If no choice is made, the result is: ALPHA=(,D).
An ellipsis indicates that the preceding item or group of items can be repeated more than once in succession.
Example: The representation
```
ALPHA[,BETA]…
```
indicates that ALPHA can appear alone or can be followed by ,BETA any number of times in succession.

Note: To designate register 0 and register 1 on a macro invocation, use (0) and (1), respectively. You cannot use a symbolic variable to designate these registers.