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Lexical Elements of the DEC Text Processing Utility Language
4.9 Reserved Words
Example 4–15 Simple Error Handler
ON_ERROR
MESSAGE ("Aborting procedure because of error.");
ABORT;
ENDON_ERROR;
4.9.5 Miscellaneous Declarations
This section describes the following DECTPU language declarations:
• EQUIVALENCE
• LOCAL
• CONSTANT
• VARIABLE
4.9.5.1 EQUIVALENCE
With the EQUIVALENCE declaration, you can create synonyms. Equivalences
work only when both real_name and synonym_name are defined at the same time.
You cannot save a section file that contains real_name and then later use that
section file to extend code that uses an EQUIVALENCE of the saved name. To
avoid problems, include all EQUIVALENCE declarations in the same compilation
unit where real_name is defined.
The equivalences can reside in different compilation units, but you must use all
of the compilation units when building the section file from scratch. If you use a
base section file that you extend interactively, you cannot make equivalences to
procedures or variables defined in the base section file.
Syntax
EQUIVALENCE synonym_name1 = real_name1, synonym_name2 = real_name2,
...;
Elements of the EQUIVALENCE Statement
real_name
A user-defined global variable or procedure name. If real_name is undefined,
DECTPU defines it as an ambiguous name. This ambiguous name can become a
variable or procedure later.
synonym_name
A name to be defined as a synonym for the real_name.
4.9.5.2 LOCAL
With the LOCAL declaration, you can identify certain variables as local variables
rather than global variables. All variables are considered to be global variables
unless you explicitly use the LOCAL declaration to identify them as local
variables. The LOCAL declaration in a procedure is optional. It must be specified
after the PROCEDURE statement and before any ON_ERROR statement.
LOCAL declarations and CONSTANT declarations can be intermixed.
The maximum number of local variables you can declare in a procedure is 255.
Local variables are initialized to 0.
4–30 Lexical Elements of the DEC Text Processing Utility Language