IP Addresses 0.0.0.0/8

[ghost]

0.0.0.0 itself is a non-routable metaddress (Wikipedia), so it shouldn't be valid. For the other addresses it's more complicated, RFC 5735:

0.0.0.0/8 - Addresses in this block refer to source hosts on "this" network. Address 0.0.0.0/32 may be used as a source address for this host on this network; other addresses within 0.0.0.0/8 may be used to refer to specified hosts on this network ([RFC1122], Section 3.2.1.3).

So they are theoretically routable (=valid), however e.g. ping does give "Invalid Argument".

I'm unsure how to deal with them. If they are actually valid, they can be removed in the rfc1918 expert, but if they are fundamentally invalid, the harmonization shouldn't accept it at all.

[navtej]

I would favour rfc1918 approach. Harmonization perhaps should not make decisions about the usefulness of data, it should accept the data as long as it is valid.

[ghost]

https://tools.ietf.org/html/rfc6890 also defines ::/128 as "Unspecified Address" and some similar network ranges