The extension defines a domain-specific language solely to write filter rules. Since the language is not Turing complete, it cannot replace bots for more complex tasks.

Significant content taken from mw:Extension:AbuseFilter/Rules format; see page history for attribution.

The edit filter captures the following data from edits. They are stored in the following variables. They can be manipulated and analyzed with various functions and operators. The data types are int (signed integer values), string (sequences of Unicode characters), bool (true and false), float (signed rational numbers), array (non-associative arrays) and null (usually an uninitialized variable).

Note that some numerical variables may be defined as a string; to act based on these variables, you may need to cast them to an int. For example, the variable timestamp is a string; to extract the date, hour etc. you must cast it to an int first (e.g. int(timestamp) % (60*60*24) === 22).

"Pre-save transformed" means after the wikitext is evaluated before saving; i.e. with template substitution. The wikitext is taken from the latest version before page save. For example, the added_lines_pst of {{subst:Mbox}} is {{#invoke:Message box|mbox}}; the added_lines is exactly {{subst:Mbox}} verbatim.

For an up-to-date list of variables, see the documentation on mediawiki.org.

+ concatenates a string with a string or other data type.

• like returns true if the left string matches the right string; this is distinct from = as the right string is treated as a glob pattern.
• in returns true if the right string contains the left string. contains is its reverse, i.e. returns true if the left string contains the right string. Note: empty strings are not contained in, nor contain, any other string (not even the empty string itself).
• rlike returns true if the left string matches the regular expression pattern in the right string. irlike is rlike with case-insensitivity. The regex engine is PCRE with support for Unicode characters. Beware, as regex is potentially expensive for two reasons:
  • The time to run a regex with quantifiers can grow exponentially with the size of an edit because of PCRE's backtracking algorithm.^[1]
  • Calling each regex has a fixed overhead, so merging multiple regexes together would be wise.^[2]
• if .. then .. else .. end and the ternary conditional operator condition ? then_value : else_value.

You can declare new variables within a condition; their scope is lexical scoping limited to the condition they appear within.

For an up-to-date list of available functions see mw:Extension:AbuseFilter/Rules format#Functions.

If a user triggers a filter, the edit filter can apply any of the following sanctions based on the severity of the offense:

• All actions triggering a filter are logged at a special page.
• The user's action can be tagged for further review.
• The user can be warned that their actions may be unconstructive.
• The user's action may be disallowed.
• The user's autoconfirmed status may be revoked (or delayed if the user doesn't hold it).

The following actions are currently not available on this wiki:

• The user's account may be blocked from editing, along with all IP addresses used in the last 7 days.
• The user's account may be removed from all privileged groups (such as sysop, bot, rollbacker).

Note: Individual sanctions can be disabled selectively. Any edit filter manager can restore autoconfirmed status in case of an error.

The condition limit is a limit imposed by the software on the total number of conditions that can be evaluated by the filters. It is arbitrarily fixed at 2,000^[5]. While the aim of this limit is to avoid performance issues, it should be noted that this isn't a good metric of how heavy a filter is: for instance, a filter using dozens of simple comparisons (and thus dozens of conditions) is much lighter than one using a single check on the all_links variable. See mw:Extension:AbuseFilter/Conditions and mw:Extension:AbuseFilter/Rules format#Performance for more details.

All edits triggering an action will produce a report at Special:AbuseLog. On this page, a brief log entry is entered. Users with the appropriate permissions may view the log summary. Users with certain higher permissions may view details on the log entry. This includes all information available to the filter when it ran, and may be useful for debugging purposes. Users with the highest level of log-viewing permissions may view private data about the action which caused the log event, such as the user's IP address. See the AbuseFilter documentation for more details on the permissions structure.

To protect the wiki against poorly configured filters, a technical limit is imposed on the maximum percentage of actions that will trigger a given filter. Other technical limits are in the process of being written.

All notifications are based on the template {{edit filter warning}}.

Standard notifications shown to a user triggering a filter action:

More information Message name, Message text ...

Message name	Message text
abusefilter-disallowed	An automated filter has identified this edit as potentially unconstructive, so it has been disallowed. If this edit is constructive, please report this error. Disruptive behavior may result in being blocked from editing. Report error
abusefilter-autopromote-blocked	An automated filter has identified this edit as potentially unconstructive, and it has been disallowed. In addition, your account has been temporarily restricted from executing some sensitive operations. If this edit is constructive, please report this error.

Close

Generic warning message is below. Admins are advised to use custom warnings.

More information Message name, Message text ...

Message name	Message text
abusefilter-warning	Warning: An automated filter has identified this edit as potentially unconstructive. Please be aware that vandalism may result in revocation of your editing privileges. If this edit is constructive, please click 'Publish changes' again, and report this error.

Close

Some existing filters and their warnings:

More information Filter and message, Message text ...

Filter and message	Message text
30: large deletions removal	Warning: An automated filter has identified this edit as removing a large amount of content. While some material on Wikipedia should be removed, such as vandalism and false or libelous information, we discourage removal of content without a valid reason. If you believe that your removal is constructive, please go to the bottom of this page and press 'Publish changes' to continue (be sure to enter an edit summary if you have not done so already). If you did not remove a large amount of content, and you believe that this edit is constructive, please report this error.
132: removal of all categories all categories removed	Warning: An automated filter has identified this edit as removing all categories from an article, which is potentially unconstructive. Categories are present as text like [[Category:XYZ]] at the bottom of articles, and should not generally be all removed. Please be aware that vandalism may result in revocation of your editing privileges. If this edit is constructive, please click 'Publish changes' again, and report this error.

Close

If a filter is set to warn and disallow, then a user clicking "Save page" will alternatively see that warning and standard disallowed message.