problems with printf: hex with capital or small letters?



Hello,

I got now Maxima running with Ecl version post-11.1.1, but there is
one change of behaviour:

printf(false,"~x",11)

returned "B" before, while now it returns "b" (in general: capital letters
before, small letters now).

I can't find a precise definition of printf (Maxima refers
to using some Lisp reference, but I can't find a Lisp reference
which is precise enough).

Are both outputs possible? Can it be sometimes "b", sometimes "B" ?
Or is only one form true (this would be best ...).

Thanks for your time

Oliver