multicharacter constant not allowed?

[Dirk Hoffmann]

I would like to use the concise form 
       
        *(unsigned int*)Ptr=(unsigned int) 'ADQR';      /* Bank name */

to initialise a (long unsigned) integer variable. I also tried without the
casts, but I get in any case the warning:

rqr.c:751: warning: multi-character character constant

back from the GNU C compiler. Do you know what's the matter here? I thought a
four-char constant could simply and uniquely define an integer value for the
compiler, but there seems to be a subtlety.