Fossil

<title>Fossil File Formats</title>
<h1 align="center">
Fossil File Formats
</h1>

The global state of a fossil repository is kept simple so that it can
endure in useful form for decades or centuries. 
A fossil repository is intended to be readable,
searchable, and extensible by people not yet born.

The global state of a fossil repository is an unordered
set of <i>artifacts</i>.
An artifact might be a source code file, the text of a wiki page,
part of a trouble ticket, or one of several special control artifacts
used to show the relationships between other artifacts within the
project.  Each artifact is normally represented on disk as a separate
file.  Artifacts can be text or binary.

In addition to the global state, 
each fossil repository also contains local state.
The local state consists of web-page formatting
preferences, authorized users, ticket display and reporting formats,
and so forth.  The global state is shared in common among all
repositories for the same project, whereas the local state is often
different in separate repositories.
The local state is not versioned and is not synchronized
with the global state.
The local state is not composed of artifacts and is not intended to be enduring.
This document is concerned with global state only.  Local state is only
mentioned here in order to distinguish it from global state.

Each artifact in the repository is named by its SHA1 hash.
No prefixes or meta information is added to an artifact before
its hash is computed.  The name of an artifact in the repository
is exactly the same SHA1 hash that is computed by sha1sum 
on the file as it exists in your source tree.</p>

Some artifacts have a particular format which gives them special
meaning to fossil.  Fossil recognizes:

<ul>
<li> [#manifest | Manifests] </li>

A manifest is a text file.  Newline characters
(ASCII 0x0a) separate the file into "cards".
Each card begins with a single
character "card type".  Zero or more arguments may follow
the card type.  All arguments are separated from each other
and from the card-type character by a single space
character.  There is no surplus white space between arguments
and no leading or trailing whitespace except for the newline 
character that acts as the card separator.

All cards of the manifest occur in strict sorted lexicographical order.
No card may be duplicated.
The entire manifest may be PGP clear-signed, but otherwise it
may contain no additional text or data beyond what is described here.

A manifest may optionally have a single B-card.  The B-card specifies
another manifest that serves as the "baseline" for this manifest.  A
manifest that has a B-card is called a delta-manifest and a manifest
that omits the B-card is a baseline-manifest.  The other manifest
identified by the argument of the B-card must be a baseline-manifest.
A baseline-manifest records the complete contents of a check-in.
A delta-manifest records only changes from its baseline.  

A manifest must have exactly one C-card.  The sole argument to
the C-card is a check-in comment that describes the check-in that
the manifest defines.  The check-in comment is text.  The following
escape sequences are applied to the text:
A space (ASCII 0x20) is represented as "\s" (ASCII 0x5C, 0x73).  A
newline (ASCII 0x0a) is "\n" (ASCII 0x5C, x6E).  A backslash 
(ASCII 0x5C) is represented as two backslashes "\\".  Apart from
space and newline, no other whitespace characters are allowed in
the check-in comment.  Nor are any unprintable characters allowed
in the comment.

A manifest must have exactly one D-card.  The sole argument to
the D-card is a date-time stamp in the ISO8601 format.  The

A manifest has zero or one N-cards.  The N-card specifies the mimetype for the
text in the comment of the C-card.  If the N-card is omitted, a default mimetype
is used.

A manifest has zero or one P-cards.  Most manifests have one P-card.
The P-card has a varying number of arguments that
define other manifests from which the current manifest
is derived.  Each argument is a 40-character lowercase 
hexadecimal SHA1 of a predecessor manifest.  All arguments
to the P-card must be unique within that card.
The first argument is the SHA1 of the direct ancestor of the manifest.
Other arguments define manifests with which the first was
merged to yield the current manifest.  Most manifests have
a P-card with a single argument.  The first manifest in the
project has no ancestors and thus has no P-card or (depending
on the Fossil version) an empty P-card (no arguments).

A manifest has zero or more Q-cards.  A Q-card is similar to a P-card
in that it defines a predecessor to the current check-in.  But
whereas a P-card defines the immediate ancestor or a merge
ancestor, the Q-card is used to identify a single check-in or a small
range of check-ins which were cherry-picked for inclusion in or
exclusion from the current manifest.  The first argument of
the Q-card is the artifact ID of another manifest (the "target")
which has had its changes included or excluded in the current manifest.  
The target is preceded by "+" or "-" to show inclusion or
exclusion, respectively.  The optional second argument to the
Q-card is another manifest artifact ID which is the "baseline"
for the cherry-pick.  If omitted, the baseline is the primary
parent of the target.  The
changes included or excluded consist of all changes moving from
the baseline to the target.  

The Q-card was added to the interface specification on 2011-02-26.  
Older versions of Fossil will reject manifests that contain Q-cards.

A manifest may optionally have a single R-card.  The R-card has
a single argument which is the MD5 checksum of all files in 
the check-in except the manifest itself.  The checksum is expressed
as 32 characters of lowercase hexadecimal.   The checksum is
computed as follows:  For each file in the check-in (except for
the manifest itself) in strict sorted lexicographical order, 
take the pathname of the file relative to the root of the
repository, append a single space (ASCII 0x20), the
size of the file in ASCII decimal, a single newline
character (ASCII 0x0A), and the complete text of the file.
Compute the MD5 checksum of the result.

A manifest might contain one or more T-cards used to set

Each manifest has a single U-card.  The argument to the U-card is
the login of the user who created the manifest.  The login name
is encoded using the same character escapes as is used for the
check-in comment argument to the C-card.

A manifest must have a single Z-card as its last line.  The argument
to the Z-card is a 32-character lowercase hexadecimal MD5 hash
of all prior lines of the manifest up to and including the newline 
character that immediately precedes the "Z".  The Z-card is 
a sanity check to prove that the manifest is well-formed and
consistent.

A sample manifest from Fossil itself can be seen
[/artifact/28987096ac | here].

<a name="cluster"></a>
<h2>2.0 Clusters</h2>

A cluster is an artifact that declares the existence of other artifacts.
Clusters are used during repository synchronization to help 
reduce network traffic.  As such, clusters are an optimization and
may be removed from a repository without loss or damage to the
underlying project code.

Clusters follow a syntax that is very similar to manifests.
A cluster is a line-oriented text file.  Newline characters
(ASCII 0x0a) separate the artifact into cards.  Each card begins with a single
character "card type".  Zero or more arguments may follow
the card type.  All arguments are separated from each other
and from the card-type character by a single space
character.  There is no surplus white space between arguments
and no leading or trailing whitespace except for the newline 
character that acts as the card separator.
All cards of a cluster occur in strict sorted lexicographical order.
No card may be duplicated.
The cluster may not contain additional text or data beyond 
what is described here.
Unlike manifests, clusters are never PGP signed.

Allowed cards in the cluster are as follows:

<blockquote>
<b>M</b> <i>artifact-id</i><br />
<b>Z</b> <i>checksum</i>
</blockquote>

A cluster contains one or more "M" cards followed by a single "Z"
card.  Each M card has a single argument which is the artifact ID of 
another artifact in the repository.  The Z card works exactly like
the Z card of a manifest.  The argument to the Z card is the
lower-case hexadecimal representation of the MD5 checksum of all
prior cards in the cluster.  The Z-card is required.

An example cluster from Fossil can be seen
[/artifact/d03dbdd73a2a8 | here].

second argument is the 40 character lowercase artifact ID of the artifact
to which the tag is to be applied. The
first value is the tag name.  The first character of the tag
is either "+", "-", or "*".  The "+" means the tag should be added
to the artifact.  The "-" means the tag should be removed.
The "*" character means the tag should be added to the artifact
and all direct descendants (but not descendants through a merge) down
to but not including the first descendant that contains a 
more recent "-", "*", or "+" tag with the same name.
The optional third argument is the value of the tag.  A tag
without a value is a Boolean.

When two or more tags with the same name are applied to the
same artifact, the tag with the latest (most recent) date is
used.

Some tags have special meaning.  The "comment" tag when applied
to a check-in will override the check-in comment of that check-in
for display purposes.  The "user" tag overrides the name of the
check-in user.  The "date" tag overrides the check-in date.
The "branch" tag sets the name of the branch that at check-in
belongs to.  Symbolic tags begin with the "sym-" prefix.

The U card is the name of the user that created the control 
artifact.  The Z card is the usual required artifact checksum.

An example control artifacts can be seen [/info/9d302ccda8 | here].


<a name="wikichng"></a>
<h2>4.0 Wiki Pages</h2>

<b>Z</b> <i>checksum</i>
</blockquote>

The D card is the date and time when the wiki page was edited.
The P card specifies the parent wiki pages, if any.  The L card
gives the name of the wiki page.  The optional N card specifies
the mimetype of the wiki text.  If the N card is omitted, the
mimetype is assumed to be text/x-fossil-wiki.  
The U card specifies the login
of the user who made this edit to the wiki page.  The Z card is
the usual checksum over the entire artifact and is required.

The W card is used to specify the text of the wiki page.  The
argument to the W card is an integer which is the number of bytes
of text in the wiki page.  That text follows the newline character

J cards specify changes to the "value" of "fields" in the ticket.
If the <i>value</i> parameter of the J card is omitted, then the
field is set to an empty string.
Each fossil server has a ticket configuration which specifies the fields its
understands.  The ticket configuration is part of the local state for
the repository and thus can vary from one repository to another.
Hence a J card might specify a <i>field</i> that do not exist in the 
local ticket configuration.  If a J card specifies a <i>field</i> that
is not in the local configuration, then that J card
is simply ignored.

The first argument of the J card is the field name.  The second
value is the field value.  If the field name begins with "+" then
the value is appended to the prior value.  Otherwise, the value
on the J card replaces any previous value of the field.
The field name and value are both encoded using the character
escapes defined for the C card of a manifest.

An example ticket-change artifact can be seen
[/artifact/91f1ec6af053 | here].

<a name="attachment"></a>
<h2>6.0 Attachments</h2>

An attachment artifact associates some other artifact that is the
attachment (the source artifact) with a ticket or wiki page or 
technical note to which
the attachment is connected (the target artifact).
The following cards are allowed on an attachment artifact:

<blockquote>
<b>A</b> <i>filename target</i> ?<i>source</i>?<br />
<b>C</b> <i>comment</i><br />
<b>D</b> <i>time-and-date-stamp</i><br />
<b>N</b> <i>mimetype</i><br />
<b>U</b> <i>user-name</i><br />
<b>Z</b> <i>checksum</i>
</blockquote>

The A card specifies a filename for the attachment in its first argument.
The second argument to the A card is the name of the wiki page or
ticket or technical note to which the attachment is connected.  The
third argument is either missing or else it is the 40-character artifact 
ID of the attachment itself.  A missing third argument means that the
attachment should be deleted.

The C card is an optional comment describing what the attachment is about.
The C card is optional, but there can only be one.

A single D card is required to give the date and time when the attachment

<b>W</b> <i>size</i> <b>\n</b> <i>text</i> <b>\n</b><br />
<b>Z</b> <i>checksum</i>
</blockquote>

The C card contains text that is displayed on the timeline for the
technote.  The C card is optional, but there can only be one.

A single D card is required to give the date and time when the 
technote artifact was created.  This is different from the time at which
the technote appears on the timeline.

A single E card gives the time of the technote (the point on the timeline
where the technote is displayed) and a unique identifier for the technote.
When there are multiple artifacts with the same technote-id, the one with
the most recent D card is the only one used.  The technote-id must be a

name means that tags can only be add and they can only be non-propagating
tags.  In a technote, T cards are normally used to set the background
display color for timelines.

The optional U card gives name of the user who entered the technote.

A single W card provides wiki text for the document associated with the
technote.  The format of the W card is exactly the same as for a 
[#wikichng | wiki artifact].

The Z card is the required checksum over the rest of the artifact.


<a name="summary"></a>
<h2>8.0 Card Summary</h2>