[giftfile-dev] certificate format: rights

[Anthony Carrico]

I'd like to tweak the Certificate format. The Certificate schema's
current subversion URL is:

  http://giftfile.org/depot/trunk/giftfile/software/giftfile-system/xml/schema/rng/certificate.rng

Here is the current Rights element definition (call it syntax A):

  <define name="Rights">
    <element name="Rights"><ref name="RightsType"/></element>
  </define>

  <define name="RightsType">
    <choice>
      <element name="License">
        <ref name="URI"/>
        <oneOrMore>
          <element name="Copyright">
            <element name="Year"><ref name="year"/></element>
            <element name="Claimant"><text/></element>
          </element>
        </oneOrMore>
      </element>
      <element name="PublicDomain">
        <element name="Year"><ref name="year"/></element>
        <element name="Author"><text/></element>
      </element>
      <element name="And"><oneOrMore><ref name="RightsType"/></oneOrMore></element>
      <element name="Or"><oneOrMore><ref name="RightsType"/></oneOrMore></element>
    </choice>
  </define>

The biggest problem with syntax A is that Rights can nest arbitrarily.
This is challenging from a user interface point of view, both for
input and output. It also leads to crazy expressions like:
  ((BSD (Copyright 2002 Foo-san)) Or (Public Domain 2002 Foo-san))
or
  ((MIT (Copyright 2002 Foo-san)) Or (MIT (Copyright 2002 Bar-san)))

In reality, we only want:
 1. "or" among licenses (for dual licensed works).
 2. "and" among copyright and public domain expressions (for combined
works).

It would be nice keep the ability to collect a bunch of copyrights
under the license, since this is the common case for a work with a
bunch of authors.

This version does so (call it syntax B):

  <define name="Rights">
    <element name="Rights"><ref name="RightsType"/></element>
  </define>

  <define name="RightsType">
    <oneOrMore>
      <choice>
        <element name="License">
          <oneOrMore>
            <ref name="URI"/>
          </oneOrMore>
          <oneOrMore>
            <element name="Copyright">
              <element name="Year"><ref name="year"/></element>
              <element name="Claimant"><text/></element>
            </element>
          </oneOrMore>
        </element>
        <element name="PublicDomain">
          <element name="Year"><ref name="year"/></element>
          <element name="Author"><text/></element>
        </element>
      </choice>
    </oneOrMore>
  </define>

Syntax B is concise, but is not explicit about the semantics of the
"oneOrMore" element semantics.

This version is explict (call it syntax C):

  <define name="Rights">
    <element name="Rights"><ref name="RightsType"/></element>
  </define>

  <define name="CopyrightExp">
    <element name="Copyright">
      <element name="Year"><ref name="year"/></element>
      <element name="Claimant"><text/></element>
    </element>
  </define>

  <define name="RightsClause">
    <choice>
      <element name="License">
        <choice>
          <ref name="URI"/>
          <element name="Or">
            <oneOrMore>
              <ref name="URI"/>
            </oneOrMore>
          </element>
        </choice>
        <choice>
          <ref name="CopyrightExp"/>
          <element name="Or">
            <oneOrMore>
              <ref name="CopyrightExp"/>
            </oneOrMore>
          </element>
        </choice>
      </element>
      <element name="PublicDomain">
        <element name="Year"><ref name="year"/></element>
        <element name="Author"><text/></element>
      </element>
    </choice>
  </define>

  <define name="RightsType">
      <choice>
        <ref name="RightsClause"/>
        <element name="And">
          <oneOrMore>
            <ref name="RightsClause"/>
          </oneOrMore>
        </element>
      </choice>
  </define>

...and hence more verbose, but the actual Certificates produced under
this schema aren't much more verbose.

Comments?

-- 
Anthony Carrico
http://giftfile.org