translation rework

[marqh]

updates to field code management; translations moved from rules into metarelate

All changes reviewed and committed to metarelate's metocean information store

this pull request incorporates all changes from #965 and #989, which is supercedes

this pull request also includes translations from #1145 and #1154 and may be better merged after these

[esc24]

Units of kg/kg, m3/m3? Really? Is there a reason for not having units of '1'?

[marqh]

yes, this is significantly preferred by the user community

e.g.: kg/kg and mol/mol are interpreted quite differently from certain scientific perspectives. Although both have units of '1' from a mathematical perspective, the scientific interpretation is different and our user community is keen to preserve this information.

[rhattersley]

I've certainly seen a lot of opinion that prefers "kg/kg", so I'm OK with this.

I've yet to be convinced "the scientific interpretation is different" - rather that some people use the unit as an alternative/adjunct to the standard name. But that's a different battle... 😑

[esc24]

Interesting given the units of '1' listed in the cf standard name table. I won't lose any sleep over it, but don't expect such units to be preserved if performing calculations e.g.:

>>> iris.unit.Unit('kg/kg') * 'm'
Unit('meter')

[marqh]

@pp-mo this replaces #965 which you raised.

please may you review this PR and assess whether #965 may be closed and this merged in its place?

[pp-mo]

incorporates all changes from #965 and #989, which it supercedes

checked for #989, all good

[pp-mo]

incorporates all changes from #965 and #989, which it supercedes

checked for #965, all good

[pp-mo]

Ok, looks fine now
Thanks @marqh
-- end of a long sorry saga !