User guide: relationship with WMO technical regulation

[Crocstar]

WMO Codes Registry relationship with WMO technical regulation - do we need this? Isn’t the information available to see on GitHub?

[marqh]

i think this is an important page, which key WMO people have to buy into

suggest that we write a stub and pass this onto that group to provide the key statements; we can adjust the tone around those prior to adoption if required