When editing tiddlers, you can extract text from the current tiddler into a new one that is then transcluded into the current one. This process is caused "extraclusion" and is driven by some special syntax that surrounds the text that is to be extracluded:

Main content

.extraclude newTitle

Extracluded content

.extraclude

When this content is saved, the original tiddler's text will be:

Main content

{{newTitle}}

and newTitle will contain:

Extracluded content

Multiple extraclusions can be in one document. The process works with both markdown and TiddlyWiki text.

This can be a very powerful editing tool but should be used with plenty of care and thought.