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Every language has a pool or words/expressions that are very hard to translate into other languages. So., based on my experience, I developed a so called “overlapping words” theory, according to which adequate translations of hard-to-translate words in language A are very likely to be found among similarly hard-to-translate words in language B.

In our case this elusive bureaucratese term “atti” whose meaning can range from norms and regulations to standards to legal acts to certificates and statements, etc. points us to a certain set of vague English words that are also very hard to translate, such as “framework,” “design,” “methodology,” “concept,” among others.

In this context my gut feeling makes me consider going with something like “planning framework” (singular) or “planning norms and standards” (pl.).

Hope this helps.

These will probably be regulations (laws) issued by il comune, la provincia (se esistono ancora) o la regione. An "atto" in this context is usually a legal document of some kind.