docs/title.txt

   1 title.txt
   2
   3 The MediaWiki software's "Title" class represents article titles, which are used
   4 for many purposes: as the human-readable text title of the article, in the URL
   5 used to access the article, the wikitext link to the article, the key into the
   6 article database, and so on. The class in instantiated from one of these forms
   7 and can be queried for the others, and for other attributes of the title. This
   8 is intended to be an immutable "value" class, so there are no mutator functions.
   9
  10 To get a new instance, call Title::newFromText(). Once instantiated, the
  11 non-static accessor methods can be used, such as getText(), getDBkey(),
  12 getNamespace(), etc. Note that Title::newFromText() may return false if the text
  13 is illegal according to the rules below.
  14
  15 The prefix rules: a title consists of an optional interwiki prefix (such as "m:"
  16 for meta or "de:" for German), followed by an optional namespace, followed by
  17 the remainder of the title. Both interwiki prefixes and namespace prefixes have
  18 the same rules: they contain only letters, digits, space, and underscore, must
  19 start with a letter, are case insensitive, and spaces and underscores are
  20 interchangeable. Prefixes end with a ":". A prefix is only recognized if it is
  21 one of those specifically allowed by the software. For example, "de:name" is a
  22 link to the article "name" in the German Wikipedia, because "de" is recognized
  23 as one of the allowable interwikis. The title "talk:name" is a link to the
  24 article "name" in the "talk" namespace of the current wiki, because "talk" is a
  25 recognized namespace. Both may be present, and if so, the interwiki must
  26 come first, for example, "m:talk:name". If a title begins with a colon as its
  27 first character, no prefixes are scanned for, and the colon is just removed.
  28 Note that because of these rules, it is possible to have articles with colons in
  29 their names. "E. Coli 0157:H7" is a valid title, as is "2001: A Space Odyssey",
  30 because "E. Coli 0157" and "2001" are not valid interwikis or namespaces.
  31
  32 It is not possible to have an article whose bare name includes a namespace or
  33 interwiki prefix.
  34
  35 An initial colon in a title listed in wiki text may however suppress special
  36 handling for interlanguage links, image links, and category links. It is also
  37 used to indicate the main namespace in template inclusions.
  38
  39 Once prefixes have been stripped, the rest of the title processed this way:
  40
  41 * Spaces and underscores are treated as equivalent and each  is converted to the
  42   other in the appropriate context (underscore in URL and database keys, spaces
  43   in plain text).
  44 * Multiple consecutive spaces are converted to a single space.
  45 * Leading or trailing space is removed.
  46 * If $wgCapitalLinks is enabled (the default), the first letter is  capitalised,
  47   using the capitalisation function of the content language object.
  48 * The unicode characters LRM (U+200E) and RLM (U+200F) are silently stripped.
  49 * Invalid UTF-8 sequences or instances of the replacement character (U+FFFD) are
  50   considered illegal.
  51 * A percent sign followed by two hexadecimal characters is illegal
  52 * Anything that looks like an XML/HTML character reference is illegal
  53 * Any character not matched by the $wgLegalTitleChars regex is illegal
  54 * Zero-length titles (after whitespace stripping) are illegal
  55
  56 All titles except special pages must be less than 255 bytes when encoded with
  57 UTF-8, because that is the size of the database field. Special page titles may
  58 be up to 512 bytes.
  59
  60 Note that Unicode Normal Form C (NFC) is enforced by MediaWiki's user interface
  61 input functions, and so titles will typically be in this form.
  62
  63 getArticleID() needs some explanation: for "internal" articles, it should return
  64 the "page_id" field if the article exists, else it returns 0. For all external
  65 articles it returns 0. All of the IDs for all instances of Title created during
  66 a request are cached, so they can be looked up quickly while rendering wiki text
  67 with lots of internal links. See linkcache.txt.