Thanks, errto. That was what I suspected would be the case. So do I understand correctly that if I were to do something like:

print "yep" if(defined $foo{HASH(xxx)});

then I'd not expect any print? (The xxx is the stringified octal code in the pre-stringified reference)

Also, thanks for the note on the stringified reference. I remember well (from having made the erroneous assumption quite a few times) that the key is just the stringified version of the reference and is not, itself, a referene.

Again, thanks for the info...it really helped.