The top level of the tree consists of the tiddlers that carry a particular tag, known as the <<.def "root tag">>. Tiddlers tagged with any of those make up the next level down, and so on.
At each level, the tiddlers can be [[ordered|Order of Tagged Tiddlers]] by means of the <<.field list>> field of the parent tag tiddler. They can also be ordered by the macro's <<.param sort>> parameter.
Each tiddler in the tree is normally displayed as a link. To suppress this, give the tiddler a <<.field toc-link>> field with the the value <<.value no>>. In the [[examples|Table-of-Contents Macros (Examples)]], the SecondThree tiddler is set up like this. Clicking such a tiddler in the tree causes its branch to expand or collapse.
The table of contents is generated as an HTML ordered list. The `<ol>` elements always have the class `tc-toc`. Expandable trees have the additional class `tc-toc-expandable`. Selectively expandable trees (including those in the two-panel browser) have `tc-toc-selective-expandable`.
: The title of the [[state tiddler|StateMechanism]] for noting the currently selected tiddler, defaulting to `$:/temp/toc/selectedTiddler`. It is recommended that this be a [[system tiddler|SystemTiddlers]]
;unselectedText
: The text to display when no tiddler is selected in the tree
;missingText
: The text to display if the selected tiddler doesn't exist
;template
: Optionally, the title of a tiddler to use as a [[template|TemplateTiddlers]] for transcluding the selected tiddler into the right-hand panel