add attributes to every branch that let you reorganize the tree into different views.

There is a tension between free text information retrieval that, at the lowest level, indexes all sequences of two or more characters, and hierarchical outlines. By adding attributes, especially to the "leaf" items, (and even to each branch of the hierarchy,) you allow more flexibility by letting the user specify alternate views.

Using this techniques means that you can specify a hierarch and attach leaves to it by attribute. Thus all leves with the attribute, say, "family" would be attached to a different branch in the hierarchy "people I know" than in the hierarchy "educational level attained".

Going even further, and possibly of more use, the same leaf could be attached to different branches without the problem of copying the leaf document, and the associated problem of keeping the two docs. in sync. For example, in the hierarch "education" the same person could be attached to "state primary school 123", "state secondary school abc", "university q"

What I am suggesting, named in a general way, allow some of the benefits of a relational database to be brought to a "simple" outline and note system.