This is another experimental sub-release of 3.1. Some of the new
facilities are experimental and may be changed or removed in the next
full release of SDML. Therefore you are recommended to continue with
3.1 unless you need the new facilities.

This main features of this sub-release, in addition to those provided
in 3.1a, are as follows:

	a) a version control system is provided for modules, which
makes it easier for users to keep track of different versions of the
same module. Most version control facilities are provided via a new
"Versions" pane of the module browser. This pane enables a "history"
of previous versions to be browsed and new versions created. Modules
are identified (in the module hierarchy browser and other browsers)
by a module name followed by a version name in parentheses. The
version name is followed by an asterisk if the module has been
modified since the last version was created. There may also be
modules without version names (e.g. if the module has just been
created or loaded from a previous release of SDML). However, full
versions of modules must be created before they can be saved to
files.

	b) enhanced file facilities are provided for modules.
Multiple modules can now be stored on the same file (by saving a
module together with its supermodules and/or submodules, or by saving
the whole hierarchy). When loading from module files, the user can
load all the modules at once or specify individual modules to load.
SDML checks that all required versions of supermodules are present;
if a version of a supermodule is missing, the user may request a
search of specified files/directories or substitute another version
as the supermodule. SDML also checks that all enhancements/fixes,
that may affect whether the modules can be loaded correctly, have
been filed in (if not, they can be filed in automatically).

	c) The release browser has additional menu options to enable
all fixes and/or enhancements, that have not yet been filed in, to be
filed in together. If there are any prerequisites, these are filed in
first (asking the user to confirm if appropriate).

	d) The module hierarchy browser and type hierarchy pane of
the module browser now have "add link" menu options, so that multiple
inheritance can be utilised more easily. The module hierarchy browser
also has a "change link" menu option, to make it easier to change a
module's supermodule.