Heirarchy shows the class constraint heirarchy. Its kind of useful, but not very often, since it rarely (if ever) changes. For your info, a screenshot is here: http://www-users.cs.york.ac.uk/~ndm/temp/heirarchy.png Edit is pretty useless, it invokes the editor with Hugs.Base, a file you probably have no wish to change at all. After invoking edit, you then need to create a new file and save it somewhere in your text editor. Because you already opened Hugs.Base, your editor has changed directory to the Hugs libraries, a bad place to store your work! Its faster to invoke your text editor directly, and probably less dangerous (people can easily overwrite Hugs.Base this way). Edit is still provided for the documents you load, via hyperlinks, and that is incredibly useful. Between me and the 2 other people I know who use WinHugs, none of us have ever clicked on the edit button. If it turns out there is a class of user who does use edit, I'll put it back.