<title>Wiki In Fossil</title>
<h2>Introduction</h2>

Fossil uses [/wiki_rules | wiki markup] for many things:

   *  Stand-alone wiki pages.
   *  Description and comments in [./bugtheory.wiki | bug reports].
   *  Check-in comments.
   *  [./embeddeddoc.wiki | Embedded documentation] files whose
      name ends in "wiki".
   *  [./event.wiki | Event descriptions].

The [/wiki_rules | formatting rules] for fossil wiki
are designed to be simple and intuitive.  The idea is that wiki provides
paragraph breaks, numbered and bulleted lists, and hyperlinking for
simple documents together with a safe subset of HTML for more complex
formatting tasks.

Some commentators feel that the use of HTML is a mistake and that
fossil should use the markup language of the
<i>fill-in-your-favorite</i> wiki engine instead.  That approach
was considered but was rejected for the following reasons:

  1.  There is no standard wiki markup language.  Every wiki engine does
      it a little differently.

  2.  The wiki markup used by fossil, though limited, is common to most
      other wiki engines, is intuitive, and is sufficient for 90% of
      all formatting tasks.

  3.  Where the fossil wiki markup language is insufficient, HTML is
      used.  HTML is a standard language familiar to most programmers so
      there is nothing new to learn.  And, though cumbersome, the HTML
      does not need to be used very often so is not a burden.


<h2>Stand-alone Wiki Pages</h2>

Each wiki page has its own revision history which is independent of
the sequence of check-ins (check-ins).  Wiki pages can branch and merge
just like check-ins, though as of this writing (2008-07-29) there is
no mechanism in the user interface to support branching and merging.
The current implementation of the wiki shows the version of the wiki
page that has the most recent timestamp.

In other words, if two users make unrelated changes to the same wiki
page on separate repositories and those repositories are synced,
the wiki page will fork.  The web interface will display whichever edit
was checked in last.  The other edit can be found in the history.  The
file format will support merging the branches back together, but there
is no mechanism in the user interface (yet) to perform the merge.

Every change to a wiki page is a separate 
[./fileformat.wiki | control artifact]
of type [./fileformat.wiki#wikichng | "Wiki Page"].

<h2>Embedded Documentation</h2>

Files in the source tree that use the ".wiki" suffix can be accessed
and displayed using special URLs to the fossil server.  This allows
project documentation to be stored in the source tree and accessed 
online.  (Details are described [./embeddeddoc.wiki | separately].)

Some projects prefer to store their documentation in wiki.  There is nothing
wrong with that.  But other projects prefer to keep documentation as part
of the source tree, so that it is versioned along with the source tree and
so that only developers with check-in privileges can change it.  
Embedded documentation serves this latter purpose.  Both forms of documentation
use the exact same wiki markup language.  Some projects may choose to
use both forms of documentation at the same time.  Because the same
format is used, it is trivial to move a file from wiki to embedded documentation
or back again as the project evolves.

<h2>Bug-reports and check-in comments</h2>

The comments on check-ins and the text in the descriptions of bug reports
both use wiki formatting.  Exactly the same set of formatting rules apply.
There is never a need to learn one formatting language for documentation
and a different markup for bugs or for check-in comments.
