OrderQtyData ambiguous in CrossOrdCxlRequest

Imported from previous forum

As I was browsing the FIXML 4.3 DTD (fixml4.3v20020920.dtd), I noticed that the occurance of the OrderQtyData block seems ambiguous in the CrossCxlSideGroup element (line 770). It is declared both as optional and as required, whereas fixionary says the block is required inside a CrossOrderCancelRequest message.

Did I misinterpret the DTD? When I load the DTD into Tibco’s TurboXML, it complains about the block.

cheers,
Erik van Zijst