IntervalAlgebraOperator.content has redundancies in RNC definition in dr-flat.rnc

[greenTara]

IntervalAlgebraOperator.content =
meta-roles.content,
(element arg { arg_interval.type }
| element arg { arg_interval.type }
| Interval
| Interval)

This cannot be converted back to XSD without error.

[greenTara]

This sort of XSD is not handled correctly by the converter:

maxOccurs="2" minOccurs="2"

There are 8 occurrences of this syntax in dr-flat.xsd

[greenTara]

The following patterns are affected by this issue:
Update.content
Equivalent.content
Interval.content
IntervalAlgebraOperator.content

[apaschke]

The replacement of maxOccurs="2" minOccurs="2" by a repeating the content model does not solve the problem, since the XSD to RelaxNG translator ignores the nested sequence in <xs:choice minOccurs="0">xs:sequence.