ISO Pascal reference manual

PROGRAM fail;
PROCEDURE Lost; FORWARD;
BEGIN
Lost;
END. (the definition of 'Lost' is missing]
*ERROR 27 -- the bound identifier may not be altered
The identifiers used to represent the actual bounds of a conformant array
parameter are given values each time the procedure or function containing
them is invoked. These values may not be altered by the program.
PROGRAM fail;
VAR a : ARRAY [1..5] OF char;
PROCEDURE p(a : ARRAY [low..high:integer] OF char)
BEGIN
END;
BEGIN
END.
REPEAT
high := high-1; (wrong)
a[high] := 'x';
UNTIL high = low;
p(a);
*ERROR 29 -- a constant is required here
The compiler is expecting a constant of some type.
PROGRAM fail;
CONST nothing = NIL; (NIL is not valid here)
VAR a : +..19; (+ is not a constant)
BEGIN
END.
*ERROR 30 -- an integer value is required here
This message is issued when a machine-code statement is incorrectly
specified. Machine-code is an extension to standard Pascal.
54 Pascal Issue 1