The core plug-in introduces a segregation of tiddlers. The tiddler model is central in the whole TiddlyWiki application and can be used in various roles. Because of the fact that a TiddlyWiki user works with tiddlers (taking the role of a wiki page) and tiddlers are the building blocks of the whole application (including modules, UI elements, etc.) we need to identify the internal tiddlers.

The core plug-in introduces the concept of system tiddlers. It builds on the convention that application internal tiddler names start with $:/. Then the core plug-in introduces a set of new functions to the wiki store which are used to retrieve tiddlers like getTiddlers(options) and forEachTiddler(callback, options). These functions work with all tiddlers in the store but the options parameter provides the ability to sort tiddlers by a field-name and exclude tiddlers with a specific tag. By default it doesn't return system tiddlers. To get a list of all tiddlers including system tiddlers, this must be requested explicitly via the options. If a function wants to present a list of tiddlers to the user it can use this new functions so that internal application tiddlers wouldn't clutter the resulting list. These functions are added via the wikimethod module type.