[Softwires] MAP support of IPv4 prefixes?

[Rémi Després <[e-mail]>]

Ole, co-authors of draft-mdt-softwire-mapping-address-and-port-02,

Sec. 1 says::
"the residual IPv4 over IPv6 mechanisms must be capable of...Provisioning an IPv4 prefix, an IPv4 address or a shared IPv4 address."
(We all agree, I think, that this is important.)

Sec.5.2 says:
" The MAP IPv6 address is created by concatenating the End-user IPv6 prefix with the MAP subnet-id and the interface-id as specified in Section 6."

Sec6 says:
"The Interface identifier format is based on the format specified in section 2.2 of [RFC6052], with the added PSID format field" (i.e. with at least a full embedded IPv4 address)

What should be done for a CE that is provisioned an IPv4 prefix, i.e. several IPv4 addresses, is in my understanding unclear.
Could you please clarify the intent?

Thanks,
RD