Textnet was designed and implemented by Trigg at the University of Maryland. It was developed to support the on-line scientific community in text creation, footnoting, annotating and critiquing. Textnet is a hypertext system based on a semantic network of nodes and labeled links. Nodes can be either primitive pieces of text called chunks or composite hierarchies called table of contents (tocs). There are two basic types of links: normal links and commentary links. In addition, there are about eighty different types of links with different functions [Trigg &Weiser, 1986].