Possible positional freedom of xsd might be more than is implemented

[rimachaudhari]

#79

https://github.com/RuleML/deliberation-ruleml/blob/1.03-psoa/relaxng/modules/unordered_deterministic_groups_expansion_module.rnc

argumentsForAtoms.sequence |=
  slotdepTermsForAtoms.sequence, slotTermsForAtoms.sequence,
  (((termsForAtoms.nonemptysequence.choice, repo?) | repo),
   slotdepTermsForAtoms.sequence, slotTermsForAtoms.sequence)?,
  resl?

could become

argumentsForAtoms.sequence |=
  (slotdepTermsForAtoms.sequence & slotTermsForAtoms.sequence),
  (((termsForAtoms.nonemptysequence.choice, repo?) | repo),
   (slotdepTermsForAtoms.sequence & slotTermsForAtoms.sequence))?,
  resl?

and similarly for Expr.