TOPS-20 PASCAL Language Manual - Bitsavers

PROGRAM HEADING AND DECLARATION SECTION
4.2 LABEL DECLARATIONS
A label makes a statement accessible from a GOTO statement. The label
section must list all the labels in the corresponding executable
section.
Format
where:
LABEL label [,label ... ]
label specifies an unsigned integer. When you declare more
than one label, you can specify the labels in any
order.
The label is an unsigned integer. Labels can be listed in any order
if more than one label is defined. A label can precede any statement
in the program, but can be accessed only by a GOTO statement. Within
the program, a colon (:) must be placed between the label and the
statement.
The scope of a label is the block in which it is declared. Therefore,
you can transfer control from one program unit to another program unit
in which the former is nested, for example:
PROGRAM Trial (INPUT,OUTPUT);
LABEL 7~;
PROCEDURE Max;
LABEL 50;
BEGIN
50
WRITELN ('Testins fairness of tosses');
END;
BEGIN
GO TO 75;
(*end of procedure Max*)
75 WRITELN ('Not fair! A weighted coin!');
END.
The GOTO statement in the procedure Max transfers control to the main
program statement that has the label 75. However, you cannot use a
GOTO statement in the main program to transfer control into the
procedure at label 50.
Example
LABEL 0, 6656, 778, 4352;
The label section specifies four labels: 0, 6656, 778, and 4352.
Note that the labels need not be specified in numeric order.
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