Convert docs/skin.txt and docs/title.txt to Markdown

Bug: T233244
Change-Id: I46806ee578f0b2b5ca9bcfebd9ad554baeae8b34

1 files changed, 65 insertions, 0 deletions

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