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

Outliners are typically used for computer programming, collecting or organizing ideas, as Personal information management or for project management. It is generally acknowledged that Doug Engelbart was the first to see the advantages of the expandable-outline user interface paradigm in software[citation needed]. Mind Mappers and Wikis are related types of software.


[edit] Design

The principal attribute of outline editors is that they support or enforce the use of a hierarchy. For example:

  • Editing: Sound parent-child relationships are enforced when the user modifies the document structure. For example:
    • Promoting, demoting, copying, or deleting a parent has the same effect on the children.
    • Every item entry must be within one level of its predecessor, such that each item must be a sibling or child of the preceding item (thus, no item can be a great-grandchild of the preceding item).
  • Viewing: The tool enables the user to affect the display by level. For example:
    • Applying styles by outline level (e.g., bold all 1st level items)
    • Displaying selected levels (e.g., show all 1st and 2nd level items, but none deeper).
    • Hoisting an item hides all parent and sibling items; thereby focusing, or zooming in, on a particular branch. De-hoisting again reveals the full outline.
  • Search: The tool retrieves all items that contain the query terms plus the ancestors (parent, grandparent...) that give them context.
  • File import / export: Both the content and structure of outlines are conveyed when files are imported or exported (e.g., from and to tab-indented files).

[edit] Layout

There are two basic types of outliners - one pane or intrinsic and two pane or extrinsic, each with its strengths and weaknesses. A one pane outliner is also known as an intrinsic outliner because the text itself is organized into an outline format - you can collapse or expand individual sections (such as paragraphs) of text, while keeping others in view. Everything is displayed within a single area, hence the term one pane.

One of the strengths of one pane outliners is that, because the text itself is what's structured and because you can see several nodes of text at once you can typically edit across sections more easily. The drawback is that because the structure isn't always visible, you don't have as strong an overview of the whole or ability to quickly navigate between sections as with a two pane outliner. Some word processors, such as Microsoft Word have an Outline Mode to help with structuring documents. [1][2]

A two pane outliner separates structure from content - the structure is extrinsic to the text. A tree structure with node titles is presented in one pane, and the text is shown in another. Since the structure is always clearly shown at all times separately from content, this format allowing for a quick overview of the structure and easy navigation. The drawback is that since only one node's worth of text is shown at one time and navigation has the additional step of crossing panes, the structure is more rigid, making editing across nodes more difficult. This view is similar to many file browsers and email programs (which can be thought of as three-pane outliners).[3]

[edit] File formats

Several file formats support an outline structure natively or encourage the use/creation of outline structures.

  • XML - XML's purpose is to aid information systems in sharing structured data
  • HTML/XHTML - outlines relatively trivial thanks to nested markup
  • OPML - simple XML-based format, also used for syndication feedlists
  • OML - alternative to OPML
  • RDF - (various formats) has web-oriented node & arc graph model, can be used for outline subset
  • XOXO - dedicated HTML-based microformat for outlines
  • CHM - Some people use it to keep personal notes, because it can organize them in an ordered hierarchical table.

[edit] See also

[edit] References

  1. ^ Robert S. Houghton (2005-12-31). "Outlining Tutorial for Microsoft Word". Ceap.wcu.edu. http://ceap.wcu.edu/houghton/EDELCompEduc/Themes/outline-word/outlineword.html. Retrieved on 2009-02-18. 
  2. ^ "How to create an outline in a document in a Word 2002". Support.microsoft.com. 2006-07-27. http://support.microsoft.com/kb/309365. Retrieved on 2009-02-18. 
  3. ^ "Overview of Windows Outliners". John.redmood.com. http://john.redmood.com/organizers.html. Retrieved on 2009-02-18. 

[edit] External links

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