[DAS2] unified rnc schema

[Andrew Dalke]

the unified schema document is in CVS under das/das2/das2_schemas.rnc

This is the merge of the existing rnc files, which were developed
and distributed in the spring.

There are stubs named
   types.rnc
   features.rnc
   segments.rnc
   sources.rnc

which all look like this

include "das2_schemas.rnc"

start = sources

Meaning that they import the main schema and define the root
node appropriately for each specific document type.

					Andrew
					dalke at dalkescientific.com