From Annie Hall's GardenDesigns.com

Where the variables are available as wiki markup they are shown as Variable value "{$Variable Name?}".

$AsSpacedFunction

The name of the function used to convert Wiki Words into normal, spaced strings. Defaults to 'As Spaced?'.

$AsSpacedFunction = 'MyAsSpaced';

Variable value ""

$Author

Set to the current reader, who is potentially an author (see discussion). See also $EnablePostAuthorRequired.

$AuthorGroup

The Wiki Group for user profiles. Defaults to 'Profiles'. This variable is implicit in the markup [[~AuthorName]]

$AuthorGroup = 'Users';

$AuthId

For sites using user-based authorization, tracks the "reader" or login name.

SessionAuth($pagename);

if( isset($AuthId) ) { // this person has been authenticated

$AuthPw

Request for documentation, meanwhile see here.

SessionAuth($pagename);

if( isset($AuthPw) ) { // this person has entered a password

Variable value "Pm Wiki.Basic Variables"

$BaseName

$BaseNamePatterns

Allows population of the {$BaseName} Page Variable?. The key to the hash is the pattern to be replaced and the value is the replacement string.

# If {$FullName} is 'Group.Page-Draft' then {$BaseName} is 'Group.Page'
$BaseNamePatterns['/-Draft$/'] = '';
# If {$FullName} is 'Comments-Group.Page' then {$BaseName} is 'Group.Page'
$BaseNamePatterns['/^Comments-/'] = '';

$CategoryGroup

The Wiki Group used for categories. Defaults to 'Category'. (See Categories). This variable is implicit in the markup [[!CategoryName]]

$CookiePrefix

A string prefix to be prepended to cookies set from Pm Wiki scripts. It defaults to '', but can be set to a different value to avoid conflicts with similar-named cookies from other applications, or to allow multiple wikis from the same domain to store separate cookies.

$CookiePrefix = 'pmwiki_'; # set cookie prefix to 'pmwiki_'

If you have a WikiFarm, use the following in each field's config.php to get a unique prefix for each field in the farm, thus isolating each field's cookies.

$CookiePrefix = substr($tmp = md5(__FILE__), 0, 5).'_';

Variable value "Main"

$DefaultGroup

WikiGroup used by default (on startup) when no group is specified in the URL.

Variable value "Home Page?"

$DefaultName

Name of the default Home Page? of each Wiki Group. Used when the group doesn't have a page with the same name as the group.

$DefaultPage

Startup page when Pm Wiki is called without a specified page, normally $DefaultGroup.$DefaultName.

$EnableLocalConfig

Allows/disables local/config.php customizations (usually for a farm's wikis). Can be set to zero in local/farmconfig.php to prevent the farm's wikis' local/config.php from being loaded.

$EnableLocalConfig = 0; # disable PmWiki's local/config

$EnablePGCust

Allows/disables per-page and per-group customizations. Can be set to zero in any local customization file to prevent remaining page/group customizations from being loaded.

$EnablePGCust=0; # turn off per-page/group configs

$EnableRedirect

When enabled (default), causes page redirects to automatically be performed by the browser. Setting $EnableRedirect to zero causes Pm Wiki to pause and issue a "Redirect to link" message instead. This is sometimes useful when debugging recipes to be able to see the results of actions before page redirections occur.

$EnableWikiWords

Enable WikiWord processing.

$EnableWSPre

Enables a markup rule that causes lines with leading spaces to be treated as sections of preformatted text. If set to a value greater than 1, indicates the minimum number of leading spaces required for this treatment.

$EnableWSPre = 1; # leading spaces are preformatted text

$EnableWSPre = 0; # leading spaces are normal lines of text

$EnableWSPre = 4; # 4+ spaces are preformatted text

$FTimeFmt

Can be used to override the default date format used by the "ftime" function. The default $FTimeFmt is $TimeFmt. (See Markup Expressions)

$GroupPattern

The regular expression pattern used for valid WikiGroup name specifications. Defaults to allowing any group name beginning with an uppercase letter, but can be set to limit the valid group names (see Cookbook:LimitWikiGroups).

# limit groups to Site, SiteAdmin, PmWiki, and MyGroup

$GroupPattern = '(?:Site|SiteAdmin|PmWiki|MyGroup)';

#for case-sensitive group names, note the ?-i switch:

$GroupPattern = '(?-i:Site|SiteAdmin|PmWiki|MyGroup)';

$LinkWikiWords

If set, then bare Wiki Words in a page are automatically linked to pages of the same name. Note that this value can also be affected by the (:linkwikiwords:) and (:nolinkwikiwords:) directives.

$LinkWikiWords = 1; # turn on WikiWord links

$LinkWikiWords = 0; # disable WikiWord links

$LogoutRedirectFmt

Identifies the page to which the visitor should be sent after an ?action=logout. Defaults to the current page.

$LogoutRedirectFmt = 'Site.Logout'; # ?action=logout target

$LogoutCookies

An array of cookie names to be removed when ?action=logout is invoked.

$NamePattern

The regular expression pattern used for valid page names. Defaults to allowing pages beginning with an uppercase letter or digit, followed by sequences of alphanumeric characters, hyphens, and underscores.

Variable value "Site"

$SiteGroup

Default group for storing configuration and utility pages such as Site.Search, Site.EditForm, Site.PageNotFound, etc.

$SiteAdminGroup

Default group for locked administrative pages such as SiteAdmin.AuthList, SiteAdmin.AuthUser, SiteAdmin.ApprovedUrls, etc, defaults to 'Site Admin'.

$SpaceWikiWords

If set, then Wiki Words in pages are automatically spaced according to $AsSpacedFunction. Note that this value can also be affected by the (:spacewikiwords:) and (:nospacewikiwords:) directives.

$SpaceWikiWords = 1; # turn on WikiWord spacing

$SpaceWikiWords = 0; # turn off WikiWord spacing

$TimeFmt

The format to use for dates and times, in strftime() format. The default value is '%B %d, %Y at %I:%M %p', which gives dates of the form "September 8, 2005 at 10:57 PM".

$TimeFmt = '%B %d, %Y'; # dates as "September 8, 2005"

$TimeFmt = '%Y-%m-%d'; # dates as "2005-09-08"

Variable value "pmwiki-2.2.16"

$Version

A string representing the release version of Pm Wiki.

Variable value "2002016"

$VersionNum

A number representing the release version of Pm Wiki, with the major and minor release components padded with zeroes to produce three digits. Thus, release "pmwiki-2.1.40" will have $VersionNum set to 2001040.

The first digit is a 2, the next three digits are the major release number, and the last three digits are the minor release number. Beta releases use 900-999 for the minor release number. Thus:

2.1.0          2001000
2.1.1          2001001
...
2.1.27         2001027
2.2.0-beta1    2001901
2.2.0-beta2    2001902
...
2.2.0-beta18   2001918
...
2.2.0          2002000

$WikiWordPattern

The pattern that describes a Wiki Word.

$EnableRelativePageVars

This setting controls how Page variables in included pages are understood by Pm Wiki.

$EnableRelativePageVars = 1; # Pm Wiki current default
In this case {$Name} displays the name of the physical page where it written. If {$Name} is in an included page, it will display the name of the included page. (This is currently Pm Wiki's default.)

$EnableRelativePageVars = 0; # revert to previous default
In this case {$Name} displays the name of the currently browsed page. Even if {$Name} is in an included page, it will display the name of the browsed page. This was Pm Wiki's default in versions 2.2.8 and earlier, and changed in 2.2.9, but you can revert it back with this line in config.php.

{*$Name} with an asterisk always displays the name of the currently browsed page, regardless of $EnableRelativePageVars.