ISO Pascal reference manual

*ERROR 57 -- the objects in the set constructor do not all have
the same type
When square brackets are used to construct a set value, the expressions
contained within must all yield values of the same type.
PROGRAM fail;
TYPE t1 = (this, that, other);
t2 = (here, there, everywhere);
VAR s : SET OF t1;
BEGIN
END.
s := [this, there, that]; ['there' is the wrong type}
*ERROR 58 -- the operands of are of unsuitable types
The operator < item > has been given operands to which it cannot be
applied.
PROGRAM fail;
VAR a, b, c : char;
BEGIN
END.
a := b + c; [chars cannot be added together}
*ERROR 59 -- the operands for are of incompatible types
The operator < item > has been used to operate upon operands of
different and incompatible types.
PROGRAM fail;
VAR c : boolean;
BEGIN
END.
s : SET OF char;
IF c IN s THEN writeln; [c is not a char}
*ERROR 60 -- this type does not define a range of values
Certain types in Pascal, known as 'ordinal types', define ranges of values.
These types are: integer, char, boolean and all enumerated types. In
64 Pascal Issue 1