$group = "(?P<{$i}_{$name}>" . preg_quote( $syn, '/' ) . ')'; MediaWiki API
You are looking at the HTML representation of the XML format.
HTML is good for debugging, but probably is not suitable for your application.
See complete documentation, or API help for more information. 
<?xml version="1.0"?>
<api>
  <help>
    <module>* meta=siteinfo (si) *
  Return general information about the site

This module requires read rights
Parameters:
  siprop         - Which sysinfo properties to get:
                    general               - Overall system information
                    namespaces            - List of registered namespaces and their canonical names
                    namespacealiases      - List of registered namespace aliases
                    specialpagealiases    - List of special page aliases
                    magicwords            - List of magic words and their aliases
                    statistics            - Returns site statistics
                    interwikimap          - Returns interwiki map (optionally filtered)
                    dbrepllag             - Returns database server with the highest replication lag
                    usergroups            - Returns user groups and the associated permissions
                    extensions            - Returns extensions installed on the wiki
                    fileextensions        - Returns list of file extensions allowed to be uploaded
                    rightsinfo            - Returns wiki rights (license) information if available
                    languages             - Returns a list of languages MediaWiki supports
                   Values (separate with '|'): general, namespaces, namespacealiases, specialpagealiases, magicwords, interwikimap, dbrepllag, statistics, usergroups, extensions, fileextensions, rightsinfo, languages
                   Default: general
  sifilteriw     - Return only local or only nonlocal entries of the interwiki map
                   One value: local, !local
  sishowalldb    - List all database servers, not just the one lagging the most
  sinumberingroup - Lists the number of users in user groups
Examples:
  api.php?action=query&meta=siteinfo&siprop=general|namespaces|namespacealiases|statistics
  api.php?action=query&meta=siteinfo&siprop=interwikimap&sifilteriw=local
  api.php?action=query&meta=siteinfo&siprop=dbrepllag&sishowalldb=
</module>
  </help>
</api>