This release of SDML introduces two new facilities:

	1)	A new browser called the "navigator" (described
below)

	2) On-line documentation, arranged in "documents" and
readable from a file named "sdml<release>.hlp" in the "extras"
directory. This file is read from when the documentation is accessed,
like the patches file in the same directory, so the documents do not
need to be read into the SDML image (thus saving memory).

The navigator replaces many of the old browsers in SDML, with a
uniform interface based on a tree structure of hypertext pages (known
as the "navigation hierarchy"). Each page in the hierarchy
corresponds to some underlying entity, or some aspect of an
underlying entity, that may be browsed.

A navigator window can show either the tree structure or the contents
of a particular page, or both simultaneously with the tree structure
on the left. The particular page being browsed can be selected by
clicking on an icon or a hypertext link.

The contents of a page depends on the kind of entity being browsed.
If there are any further pages below it in the tree, the contents
consists of a list of those pages (plus occasionally some additional
text). Otherwise the page may contain other kinds of information,
such as text, buttons, a hierarchy or a list of object definitions.

The navigator also provides some general capabilities, the effect of
which depends on the particular pages being selected. The "delete"
key removes the entity being browsed, if possible. Entities can also
be copied, moved or linked to by dragging an icon onto another page
or into a different window. [However, the drag-drop facility is only
currently used in limited situations, such as copying or moving
rules.]

There is a menu at the top of each navigator, providing general
facilities, such as moving back and forward between pages, opening
new browsers and obtaining help. Additional menus are also provided
in the panes of the navigator; these menus depend on the kind of page
that is selected (no menus are provided for some kinds of page).

Currently the navigator is implemented for all information within the
module hierarchy, and for the on-line documentation (documents). In
future releases of SDML, it will also be used for other browsers,
such as on objects and agents within a simulation. Since the tutorial
has not yet been rewritten for the navigator, an option is provided
(from the "settings tool" that can be opened from the "File" menu of
the launcher) to specify whether navigators or old-style browsers are
opened by default.