proper IP4/CIDR format

I got a IP4/CIDR directive in the form of:

        X.Y.Z/19

SPF rejects it.

I tested the ip4 compare routine using a format of:

       X.Y.Z.0/19

Now it works.

Is the specific domain SPF policy IP4/CIDR setup incorrect?  What is the
proper IP4/CIDR format for the above?

Thanks