A set index article (SIA) is a list article about a set of items of a specific type that also share the same (or similar) name. For example, Dodge Charger describes a set of cars, List of peaks named Signal describes a set of mountain peaks, and List of ships of the United States Navy named Enterprise describes a set of ships.
Being a set of a specific type means that the members of the set have some characteristic in common, in addition to their similarity of name. A list is an SIA only if both criteria for inclusion of an item in the list are met. For example, every entry in a list of earthquakes might include the word "earthquake", but that alone does not mean that the list is an SIA. If earthquakes were assigned names similar to how tropical storms are named, then List of earthquakes named X could be a set index (assuming of course that there are multiple earthquakes with the same name).
Fundamentally, a set index article is a type of list article. The criteria for creating, adding to, or deleting a set index article should be the same as for a stand-alone list. The style of a set index article should follow the style guidelines at Wikipedia:Stand-alone lists. A set index article can be tagged with {{Set index article}}.
A set index article is not a disambiguation page:
An SIA need not follow the formatting rules for disambiguation pages; in contrast to many restrictions stated in the disambiguation page guidelines, an SIA may contain
Sometimes there is both a disambiguation page and a set-index article organized about the same term. If the disambiguation page bears the term as its title (as is the case with Signal Mountain), then the set index article can be named "List of XXXs named YYY"; the example of List of peaks named Signal is a helpful instance.
If the circumstances allow a choice between having the (bare or unqualified) term link to a set-index page or to the disambiguation page, that term usually should be assigned as the disambiguation page's title because the disambiguation page-type accommodates the broadest variety of uses. (Nevertheless, in the rare cases where the set index article is considered the primary topic, it may be named with that term (without further qualification), with the disambiguation page accordingly being titled "YYY (disambiguation)".)
A disambiguation page should not be reclassified as a SIA (e.g., on the basis that its entries all happen to be instances of a single type). As an example, Western State Hospital is, correctly, categorized as a disambiguation page even though each of the articles it links to is literally a hospital (rather than some other type of building – or legal entity, titled work, mental state, etc., ad infinitum).
A set index article (a list of items of a specific type that share the same name, or sufficiently similar ones) may be one or more of the following:
Refer to the relevant guidelines for further details.
Place one of the following templates at the bottom of the page, using the most specific template available. If there is no specific template, you can, as {{Set index article}} explains, use the most generic template with certain sort keys to more specifically categorize articles; the template's page also explains that you can use it to place pages into child categories of Category:Set index articles.
For more information about set index articles for ships, see Wikipedia:WikiProject Ships/Guidelines § Index pages.
A summary of related policies and guidelines is given below. Editors should ensure that any set index article is compatible with these policies and guidelines. Refer to the current versions of the policies and guidelines for details.
