Main = <s> String.
NSRef		= <namespace> Ident ":".
SchemaItem	: 
                  AAS |
		  Comment
		  .

AAS = "<" [ <prefixS> NSRef ] Rest.
Rest :
		  AnnotationR |
		  AttributeR |
		  SequenceGroupR .

AnnotationR	= "annotation>".
AttributeR	= "attribute".
SequenceGroupR	= "sequence".
Comment		= "<!--" <comment> String "-->".