ISO Pascal reference manual

PROGRAM fail(input, output);
TYPE t = 1..3;
VAR x : t;
BEGIN
read(x);
CASE x of
1: writeln('one');
2: writeln('two');
3: writeln('three');
2: writeln('oops!'); [duplicate 2:1
END.
END;
*ERROR 85 -- this case label is out of range
Surprisingly, the Pascal standard does not proscribe the specification of case
labels which are outside the range of the case selector except when the
CASE is used to define record variants.
PROGRAM fail(output,input);
TYPE small = 1..3;
rec = RECORD CASE s:small OF
VAR tiny:small;
BEGIN
END.
read(tiny);
CASE tiny OF
END;
END;
1: writeln('one');
2: writeln('two');
3: writeln('three');
1: (a:integer);
2: (b:char);
3: (c:real);
4: (d:boolean); [error 4 is not in small}
4: writeln('four'); (warning 4 is not in small}
74 Pascal Issue 1