[fpc-pascal]I don't understand value typecast

[Luis Del Aguila]

In the manual explain that the value typecast doesn't work, when the type
size of the expression and the size of the type cast  not must be the same.
(page 58. ref.pdf)
But this program compile.

Var a:integer;
      b:char;
      c:boolean;
      d:word;
Begin
   a:=integer('A');
   b:=Char(4875);
   c:=boolean(100);
End.

How work the value typecast?
thanks.