any element for 'infraAttributes'
The current implementation of infraAttributes doesn't allow the addition of an 'any' element. generalInfraAttributes should be used, which offer some deeply hidden 'any' element.
Change current implementation with 'xs:all' model group to 'xs:sequence' in order to allow 'any' element directly. Remove old 'generalInfraAttributes' concept.
see also #48
Proposed solution railML 3.1
railML 3.1 does not implement infrastructure attributes like previous versions railML 2.x. Thus, the mentioned problems do not occur.
Proposed solution railML 3.x
General question to be answered: is there a need / use case for modeling infrastructure attribute groups?