Assembly identifiers are user-defined symbols representing memory
locations or numbers. A symbol can contain any number of characters drawn from alphabetics,
numerics, as well as special characters: dollar, $
; question mark,
?
; and underscore, _
.
The first character of an identifier cannot be numeric nor the
$
character. The case of alphabetics is significant, e.g.,
is not the same symbol as
Fred
fred
. Some examples of identifiers are shown here:
An_identifier
an_identifier
an_identifier1
?$_12345
An identifier cannot be one of the assembler directives, keywords, or psect flags.
An identifier that begins with at least one underscore character can be accessed from C code. Care must be taken with such symbols that they do not interact with C code identifiers. Identifiers that do not begin with an underscore can only be accessed from the assembly domain. See Equivalent Assembly Symbols for the mapping between the C and assembly domains.