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}}.

Set indexes and disambiguation

A set index article is not a disambiguation page:

  • A disambiguation page is a list of things (possibly of different types), that share the same name (or similar names).
    It is formatted for best helping the reader in navigating to topic being sought.
  • A set index article (or SIA) lists things only of one type, and is meant to provide not only navigation, but information as well.
    Just as with a typical list article, it may have metadata and other extra information about any of its entries.

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

  • red links to help editors create articles on notable entries, and
  • references (to document the respective bases for inclusion of entries).

Sometimes there will be both a disambiguation page and a set-index article organized around 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 inifitum).

Common selection criteria

A set index article (a list of items of a specific type that share the same (or similar) name) may be one or more of the following:

  • Notable list:
    The list topic has been discussed as a group or set by independent reliable sources.
    The individual entries needn't be notable in themselves.
    (See WP:LISTN.)
  • List of notable items:
    The list topic need not be notable in itself.
    Nevertheless, each of the items should be notable.
    Various red-linked entries are acceptable, if the entry is
    1. verifiably a member of the listed group, and
    2. likely to have an article on the topic in the future.
    (See WP:CSC.)
  • Short, complete list:
    The list includes every item that is verifiably a member of the group.
    It is reasonably short.
    It could be useful or interesting to readers.
    Its inclusion of items is supported by reliable sources. Lists where no entry is notable are rarely appropriate; see Wikipedia:CSC.

Refer to the relevant guidelines for further details.

Typical information

1. The information given by a set index article will depend on the specific type of items listed. For example:
  • For mountains, that information may include latitude and longitude, height, range, and political subdivisions.
  • For ships it could include type of ship, country, various dates (commission/decommission, ordered, laid down, launched), and notable battles or events the ship is associated with.
  • For a common name shared by several plants, information could include geographic range, taxonomic family, flower color, or photos.
2. Refer to the categories listed below (e.g. Category:Set indices on storms) for examples of the types of information that may be appropriate.
3. Link to the article or article section on the subject of each entry, if there is one, and to related articles, e.g. political subdivisions, battles, taxonomic families. E.g.,
4. Information need not be repeated if it is the same for all entries. There is no point in stating that ships are frigates or plants have white flowers if that is clearly true of all the entries.
5. There should be enough information on each item to differentiate it from the other items.
6. The information should have the potential to help a reader with a passing familiarity with an item to identify the one they are interested in. Such a reader might know that a ship served in World War II, or that a plant grows near where they live, but will not know the ship's pennant number or the scientific name of the plant.
7. As discussed in Wikipedia:What Wikipedia is not#Wikipedia is not an indiscriminate collection of information, data should be put in context and explained with references to independent sources. The set index should not contain a mass of minute and unexplained details.
8. As discussed in Wikipedia:Stand-alone lists#Common selection criteria, if the list includes every member of the group, it should be less than 32K in length.
9. Long lists should be structured so that a reader can readily find the item they are interested in. Alphabetical sequence, subheadings, and sortable tables may be useful.
10. The introduction to a list that contains every member of the group should identify the source(s) for the complete list, which may be online databases, gazetteers, etc. Results of a general web search are not adequate.
11. List items do not require citations if they only give information provided by the source(s) cited in the introduction to the list. If an item gives more information, that should be backed up by citations.

Tagging and categorizing an article as an SIA

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 indices.

Generic