Introduced in v5.1.19 When saving a TiddlyWiki using the save changes button, the default file name used for saving is constructed using the Title of the TiddlyWiki as entered in the Control Panel, which is stored in the tiddler $:/SiteTitle.

The value used is in the form {{$:/SiteTitle}}.html. This causes the filename to be constructed from the site Title with a .html extension.

If a tiddler named $:/config/SaveWikiButton/Filename is created, the text in that tiddler will be used as the default file name used for saving the TiddlyWiki.