Manual:$wgBrowserBlackList

Details
Browser Blacklist for unicode non compliant browsers. Contains a list of regexps : "/regexp/" matching problematic browsers. If the user-agent of a browser matches one such regex, the "safemode" field is used when editing (see the  item in Manual:Parameters to index.php for details).

Current version
From MW 1.11 onwards, this setting has the following default values:

The changes between this and the previous version are:
 * There was a change to regexes for Netscape 2-4 detection.
 * The Google Wireless Transcoder regex was added.

1.7.0
From 1.7.0 until 1.11, this setting had the following default values:

Prior to 1.7.0
From 1.4.1 to 1.6.10, this setting had the following default values:

Prior to 1.4.1
In 1.4.0, this setting had the following default value: