How can I specify an IPv6 address prefix in an ACL ?

This problem occurs on both BIND 9.3.0 and BIND 9.2.4 .

Whenever I try to specify an IPv6 address prefix in an ACL,
named-checkconf fails with :

missing ';' before '/'
expected IP match list element near '/'


I've tried:

acl test {
fec0:ac10:40a5:1/64;
};

acl test {
fec0:ac10:40a5:0001/64;
};

acl test {
fec0:ac10:40a5:0001 / 64;
};

acl test {
fec0:ac10:40a5:1:/64;
};

acl test {
f.e.c.0.a.c.1.0.4.0.a.5.0.0.0.1/64;
};

The Bv9ARM states:

"
The elements which constitute an address match list can be any of the
following:

* an IP address (IPv4 or IPv6)

* an IP prefix (in the `/'-notation)
"

Since both IPv4 and IPv6 addresses can be specified,
I'm led to assume "IP prefix" means 'IPv4 or IPv6 prefix' - am I wrong ?

Am I missing something ?
Anyone have any ideas how to do this ?