[Platforms] Nulls

[Roy Lowry]

Dear All,

Another issue waiting in the wings is the ship code for 'unknown' - we've actually got 68 different ones: one per country.  Embedding semantics in 'null metadata' is bad practice, but we do have one code (ZZ99) that means 'unknown' and nothing else.

SeaDataNet needs an 'unknown' ship code, so I've proposed 'ZZ99'.  If nobody has any objections I suggest we deprecate the other 67 mapped to 'ZZ99' in the same way as the 'multiple hull' issue has been handeled within RECO.

Cheers, Roy.