Changed maxlength to be either 32 (v4) or 128 (v6) when AS0 is set as origin ASN.
"""
4. Disavowal of Routing Origination
A ROA is a positive attestation that a prefix holder has authorized
an AS to originate a route for this prefix into the inter-domain
routing system. It is possible for a prefix holder to construct an
authorization where no valid AS has been granted any such authority
to originate a route for an address prefix. This is achieved by
using a ROA where the ROA's subject AS is one that must not be used
in any routing context. Specifically, AS 0 is reserved by the IANA
such that it may be used to identify non-routed networks [IANA-AS].
A ROA with a subject of AS 0 (AS 0 ROA) is an attestation by the
holder of a prefix that the prefix described in the ROA, and any more
specific prefix, should not be used in a routing context.
The route validation procedure, described in Section 2, will provide
a "valid" outcome if any ROA matches the address prefix and origin
AS, even if other valid ROAs would provide an "invalid" validation
outcome if used in isolation. Consequently, an AS 0 ROA has a lower
relative preference than any other ROA that has a routable AS as its
subject. This allows a prefix holder to use an AS 0 ROA to declare a
default condition that any route that is equal to or more specific
than the prefix to be considered "invalid", while also allowing other
concurrently issued ROAs to describe valid origination authorizations
for more specific prefixes.
By convention, an AS 0 ROA should have a maxLength value of 32 for
IPv4 addresses and a maxlength value of 128 for IPv6 addresses;
although, in terms of route validation, the same outcome would be
achieved with any valid maxLength value, or even if the maxLength
element were to be omitted from the ROA.
Also by convention, an AS 0 ROA should be the only ROA issued for a
given address prefix; although again, this is not a strict
requirement. An AS 0 ROA may coexist with ROAs that have different
subject AS values; although in such cases, the presence or lack of
presence of the AS 0 ROA does not alter the route's validity state in
any way.
"""