Relevance and notability are both straight-forward concepts. This page merely clarified what, specifically, is allotted.
Relevance
Text
Text outside the intro paragraph must be in-game information, and not real-life information. No comparisons to other weapons or games, no exceptions.
Images and videos
Images must be game-relevant. This means either developer interviews, game previews, etc. No "tactics" videos, or personal images (such as PimpMyGun images or real-life photos). If a non-developer/publisher video, which is completely objective, is desired, it may be added.
Notability
Notability is how important something is within the game universe. It is decided on a case by case basis.
Vehicles
Any usable or important vehicles may be added. so, for instance, an AH-64 Apache, which is usable, must have an article, but an unusable, unimportant vehicle like a van must not have an article. Or an important vehicle like an EMP Satellite may have an article, even though it may be decided that it is not notable enough.
Weapons
All usable weapons must have an article. Unusable weapons may not (or in some cases, a weapon that is unusable but seeable in the singleplayer but usable in the multiplayer must have an article).
Attachments
All attachments have an article they are notable.
Terrain, landscape, towns, locations, etc
If it a notable area, it must have an article. So for instance, Colorado has an article.
Factions
Factions, including both armed factions (such as the American Resistance and the Greater Korean Republic) and non-military factions (such as a company in-game) must have an article. Factions that are behind the scenes (such as Canada), unless having some major part in-game, may not have an article.
Characters
Individual characters are notable. Non-notable characters include individual cannon-fodder, so for instance a Korean Officer may not have an article. However, a group of characters with similar attributes (so for instance, a distinct type of enemy or friendly soldier) have articles, listing their common, shared attributes, their armament, and any variations that appear more than once, as well as once-off soldiers who play a major role (who are documented as a separate section, with his or her own "background" section and any major things they do).