The Enclose With New Document command encloses the current selection with a New Document template (screenshot below).
The New Document template contains an Initial Document Section that contains the design selection that was highlighted when the Enclose With New Document command was selected. In the screenshot above, the TOC design component was selected and enclosed with a New Document template. Content can now be entered in the Initial Document Section. If desired, additional Document Sections can be appended to the Initial Document Section via the Insert | Insert Page / Column / Document Section command.
A New Document template creates a new document in the output. As a result, the output will consist of multiple output-documents.
For a detailed description of how to work with multiple output-documents, see the section, Multiple Document Output.