Category is the corporate need the template serves: formation, equity, ops or sales. Formation and equity are the securities-class categories, which is what forces counselReview.
CounselReview marks a template whose rendered documents open with the counsel notice. True for every formation and equity template whatever an override sends: the engine prepends the notice and no caller can suppress it.
Fields declares the merge fields the body consumes — every key a generation must supply, each with its human label. All are REQUIRED: a missing one is refused rather than rendered as a blank into a contract.
Origin is "builtin" for a template the platform ships or "org" for one this org saved. It separates the catalog every tenant sees from this tenant's own.
Version is which version of this template the caller's org resolves to. A built-in is version 1; the org's first override is 2 and each save increments, so an override version never collides with the built-in's.