problem / in zonename as RFC2317 with bind9

[Thomas Börnert]

hi list,

i would establish a reverse delegation as descriped in
RFC2317. i've the following zone definition

zone "240/240.111.111.111.in-addr.arpa" IN {
        type master;
        file "240.111.111.111.in-addr.arpa";
        allow-transfer { dnsservers; };
};

with bind 9.2 it was running with 9.3 i got the following
error:

zone 240/28.111.111.111.in-addr.arpa/IN: loading master file 
240.111.111.111.in-addr.arpa: bad owner name (check-names)

with the option

check-names ignore;

i would working.

also if i replace the / with - it works

zone "240-240.111.111.111.in-addr.arpa" IN {
        type master;
        file "240.111.111.111.in-addr.arpa";
        allow-transfer { dnsservers; };
};

has everyone an idea what is wrong here ?

Thanks

Thomas