Metafields Unprocessable Entity by mattywarr

Hi,

We are getting some errors when creating Metafields "Unprocessable entity". is there anywhere that documents the exact rules of the field requirements that are in place when making the request?

We are developing a feature in our app which will create and manipulate the Metafield and the data within it for each product. 

We are trying a short namespace "g2" and of course we want to define some rules in our interface which prevents the user from submitting unprocessable entity requests.

Thanks,

Matt