HLASM Language Reference

Sequence Symbols
Redefined Operation Codes: If an operation code is redefined using the OPSYN
instruction then the value returned by a subsequent operation code attribute
reference represents the new operation code. If the operation code is deleted using
the OPSYN instruction then the value returned is U.
Sequence Symbols
You can use a sequence symbol in the name field of a statement to branch to that
statement during conditional assembly processing, thus altering the sequence in
which the assembler processes your conditional assembly and macro instructions.
You can select the model statements from which the assembler generates
assembler language statements for processing at assembly time.
A sequence symbol consists of a period (.) followed by an alphabetic character,
followed by 0 to 61 alphanumeric characters.
Examples:
.BRANCHING_LABEL#1
.A
Sequence symbols can be specified in the name field of assembler language
statements and model statements; however, sequence symbols must not be used
as name entries in the following assembler instructions:
| ALIAS EQU OPSYN SETC
| AREAD ICTL SETA SETAF
| CATTR LOCTR SETB SETCF
| DXD
Also, sequence symbols cannot be used as name entries in macro prototype
instructions, or in any instruction that already contains an ordinary or a variable
symbol in the name field.
Sequence symbols can be specified in the operand field of an AIF or AGO
instruction to branch to a statement with the same sequence symbol as a label.
Scope: A sequence symbol has a local scope. Thus, if a sequence symbol is
used in an AIF or an AGO instruction, the sequence symbol must be defined as a
label in the same part of the program in which the AIF or AGO instruction appears;
that is, in the same macro definition or in open code.
Symbolic Parameters: If a sequence symbol appears in the name field of a
macro instruction, and the corresponding prototype statement contains a symbolic
parameter in the name field, the sequence symbol does not replace the symbolic
parameter wherever it is used in the macro definition. The value of the symbolic
parameter is a null character string.
Example:
Chapter 9. How to Write Conditional Assembly Instructions 339