docs/title.txt

   1 title.txt
   2
   3 The MediaWiki software's "Title" class represents article
   4 titles, which are used for many purposes: as the human-readable
   5 text title of the article, in the URL used to access the article,
   6 the wikitext link to the article, the key into the article
   7 database, and so on. The class in instantiated from one of
   8 these forms and can be queried for the others, and for other
   9 attributes of the title. This is intended to be an
  10 immutable "value" class, so there are no mutator functions.
  11
  12 To get a new instance, call Title::newFromText(). Once instantiated,
  13 the non-static accessor methods can be used, such as getText(),
  14 getDBKey(), getNamespace(), etc. Note that Title::newFromText() may
  15 return false if the text is illegal according to the rules below.
  16
  17 The prefix rules: a title consists of an optional interwiki
  18 prefix (such as "m:" for meta or "de:" for German), followed
  19 by an optional namespace, followed by the remainder of the
  20 title. Both interwiki prefixes and namespace prefixes have
  21 the same rules: they contain only letters, digits, space, and
  22 underscore, must start with a letter, are case insensitive,
  23 and spaces and underscores are interchangeable.  Prefixes end
  24 with a ":". A prefix is only recognized if it is one of those
  25 specifically allowed by the software. For example, "de:name"
  26 is a link to the article "name" in the German Wikipedia, because
  27 "de" is recognized as one of the allowable interwikis. The
  28 title "talk:name" is a link to the article "name" in the "talk"
  29 namespace of the current wiki, because "talk" is a recognized
  30 namespace. Both may be present, and if so, the interwiki must
  31 come first, for example, "m:talk:name". If a title begins with
  32 a colon as its first character, no prefixes are scanned for,
  33 and the colon is just removed. Note that because of these
  34 rules, it is possible to have articles with colons in their
  35 names. "E. Coli 0157:H7" is a valid title, as is "2001: A Space
  36 Odyssey", because "E. Coli 0157" and "2001" are not valid
  37 interwikis or namespaces.
  38
  39 It is not possible to have an article whose bare name includes
  40 a namespace or interwiki prefix.
  41
  42 An initial colon in a title listed in wiki text may however
  43 suppress special handling for interlanguage links, image links,
  44 and category links. It is also used to indicate the main
  45 namespace in template inclusions.
  46
  47 Once prefixes have been stripped, the rest of the title processed
  48 this way:
  49
  50 * Spaces and underscores are treated as equivalent and each
  51 is converted to the other in the appropriate context (underscore in
  52 URL and database keys, spaces in plain text).
  53 * Multiple consecutive spaces are converted to a single space.
  54 * Leading or trailing space is removed.
  55 * If $wgCapitalLinks is enabled (the default), the first letter is
  56 capitalised, using the capitalisation function of the content language
  57 object.
  58 * The unicode characters LRM (U+200E) and RLM (U+200F) are silently
  59 stripped.
  60 * Invalid UTF-8 sequences or instances of the replacement character
  61 (U+FFFD) are considered illegal.
  62 * A percent sign followed by two hexadecimal characters is illegal
  63 * Anything that looks like an XML/HTML character reference is illegal
  64 * Any character not matched by the $wgLegalTitleChars regex is illegal
  65 * Zero-length titles (after whitespace stripping) are illegal
  66
  67 All titles except special pages must be less than 255 bytes when
  68 encoded with UTF-8, because that is the size of the database field.
  69 Special page titles may be up to 512 bytes.
  70
  71 Note that Unicode Normal Form C (NFC) is enforced by MediaWiki's user
  72 interface input functions, and so titles will typically be in this
  73 form.
  74
  75 getArticleID() needs some explanation: for "internal" articles,
  76 it should return the "page_id" field if the article exists, else
  77 it returns 0. For all external articles it returns 0. All of
  78 the IDs for all instances of Title created during a request are
  79 cached, so they can be looked up quickly while rendering wiki
  80 text with lots of internal links. See linkcache.txt.