TreeLine is a free

Free software

Free software, software libre or libre software is software that can be used, studied, and modified without restriction, and which can be copied and redistributed in modified or unmodified form either without restriction, or with restrictions that only ensure that further recipients can also do...

 and simple outliner

Outliner

An outliner is a computer program that allows text to be organized into discrete sections that are related in a tree structure or hierarchy. Text may be collapsed into a node, or expanded and edited....

 with advanced data element definition and export abilities. It uses a basic tree structure

Tree (data structure)

In computer science, a tree is a widely-used data structure that emulates a hierarchical tree structure with a set of linked nodes.Mathematically, it is an ordered directed tree, more specifically an arborescence: an acyclic connected graph where each node has zero or more children nodes and at...

 to organize information, and allows the user to define different types of nodes and leaves.

Export

TreeLine outlines can be exported as HTML, per-data type user defined formatting. In addition, it supports exporting outlines as an OpenDocument

OpenDocument

The Open Document Format for Office Applications is an XML-based file format for representing electronic documents such as spreadsheets, charts, presentations and word processing documents....

 ODT

OpenDocument

The Open Document Format for Office Applications is an XML-based file format for representing electronic documents such as spreadsheets, charts, presentations and word processing documents....

 file, various delimited text file formats, and as 'plain' XML.

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