What is the meaning of
Does it mean
If I write a document, what requirements must it have before I can say "it's a normative document" / "it's a non-normative document"?
I typically see this in reference to standards and technical documents. A normative definition or statement is one that should be taken as authoritative or imperative (i.e., a should or a must), while a non-normative one is one that bears no such restriction.
Synonyms for normative would include prescriptive, so synonyms of non-normative could range from descriptive to declarative to informal or casual, depending on context.
Basically, it means "informal" or "nonstandard", as from the Free Online Dictionary: