Re: etc/schema

[Richard M. Stallman]

    # Permission to use, copy, modify and distribute the DocBook DTD
    # and its accompanying documentation for any purpose and without fee
    # is hereby granted in perpetuity, provided that the above copyright
    # notice and this paragraph appear in all copies.  The copyright
    # holders make no representation about the suitability of the DTD for
    # any purpose.  It is provided "as is" without expressed or implied
    # warranty.
    #
    # If you modify the DocBook DTD in any way, except for declaring and
    # referencing additional sets of general entities and declaring
    # additional notations, label your DTD as a variant of DocBook.  See
    # the maintenance documentation for more information.

That looks like a free software license, but one needs to see
the "maintenance documentation" to we sure.  Where is that?

Lacking any other information, we have to assume that this
only covers the files in which it is present.