I think Doug asked for lightweight. HTML and XML markup aren't lightweight by any means, although a special purpose plain-text oriented XML (LTML for language-tagged markup language) might not be that much more involved than plane 14 tags. It would also have the advantage that standard XSLT tools could be used to translate between LTML and XHTML, etc.
Murray Michael Everson wrote: >At 21:50 -0800 2002-11-12, Doug Ewell wrote: >>3. Is there any method of tagging, anywhere, that is lighter-weight >>than Plane 14? (Corollary: Is "lightweight" important?) >HTML and XML markup?