/usr/include/GNUstep/DOM/ is in libsope-dev 3.2.6-1.
This file is owned by root:root, with mode 0o755.
..
/usr/include/GNUstep/DOM/DOM.h
/usr/include/GNUstep/DOM/DOMAttribute.h
/usr/include/GNUstep/DOM/DOMBuilder.h
/usr/include/GNUstep/DOM/DOMBuilderFactory.h
/usr/include/GNUstep/DOM/DOMCDATASection.h
/usr/include/GNUstep/DOM/DOMCharacterData.h
/usr/include/GNUstep/DOM/DOMComment.h
/usr/include/GNUstep/DOM/DOMDocument.h
/usr/include/GNUstep/DOM/DOMDocumentFragment.h
/usr/include/GNUstep/DOM/DOMDocumentType.h
/usr/include/GNUstep/DOM/DOMElement.h
/usr/include/GNUstep/DOM/DOMEntity.h
/usr/include/GNUstep/DOM/DOMEntityReference.h
/usr/include/GNUstep/DOM/DOMImplementation.h
/usr/include/GNUstep/DOM/DOMNamedNodeMap.h
/usr/include/GNUstep/DOM/DOMNode+Enum.h
/usr/include/GNUstep/DOM/DOMNode+QueryPath.h
/usr/include/GNUstep/DOM/DOMNode.h
/usr/include/GNUstep/DOM/DOMNodeWalker.h
/usr/include/GNUstep/DOM/DOMNotation.h
/usr/include/GNUstep/DOM/DOMPYXOutputter.h
/usr/include/GNUstep/DOM/DOMProcessingInstruction.h
/usr/include/GNUstep/DOM/DOMProtocols.h
/usr/include/GNUstep/DOM/DOMQueryPathExpression.h
/usr/include/GNUstep/DOM/DOMSaxBuilder.h
/usr/include/GNUstep/DOM/DOMSaxHandler.h
/usr/include/GNUstep/DOM/DOMText.h
/usr/include/GNUstep/DOM/DOMXMLOutputter.h
/usr/include/GNUstep/DOM/EDOM.h