Modify the OpenSymbol.sfd and generate opens___.ttf from it with fontforge. The
.sfd is the canonical source for the .ttf

Every new version of the font should increase the font version. This is
important so that when two versions of the font are installed, e.g.  one
bundled inside the office installation, and one already installed on the system
that the most recent font can be detected and favoured.

Bumping the font version is easiest done manually by bumping the two places in
the .sfd where the version is mentioned, e.g.

-Version: 102.3
+Version: 102.4

-LangName: 1033 "" "" "Regular" "OpenSymbol" "" "Version 102.3"
+LangName: 1033 "" "" "Regular" "OpenSymbol" "" "Version 102.4"

The glyph names in the font should follow Adobe Glyph list for new fonts
(http://partners.adobe.com/public/developer/en/opentype/aglfn13.txt) or just the
uniXXXX scheme (see http://www.adobe.com/devnet/opentype/archives/glyph.html for
the rationale).

Fragments of OpenSymbol are mapped internally to a number of other
fonts for interoperability purposes. See
unotools/source/misc/fontcvt.cxx pwrt.  the StarSymbol conversion
tables.