Only the DOM_Element node type has attributes. All other node types have a NULL attributes member. Child nodes are accessable through the childNodes DOM_NodeList member and the firstChild, lastChild, previousSibling, and nextSibling members. Not all element types have child nodes.

In DOMC node inheritance is emulated with simple typedef statements and a union that contains all possible subclass attributes. To access a child interface specific attribute it may be necessary to access it through this union. For example the systemId of a notation node is currently only accessible through the union like:

DOM_String *sysid;
...
sysid = node->u.Notation.systemId;

The all-important DOM_Node structure follows although some fields are left out in the interest of brevity. It may be necessary to look at this structure in the domc.h header.

struct DOM_Node {
	DOM_String *nodeName;
	DOM_String *nodeValue;
	unsigned short nodeType;
	DOM_Node *parentNode;
	DOM_NodeList *childNodes;
	DOM_Node *firstChild;
	DOM_Node *lastChild;
	DOM_Node *previousSibling;
	DOM_Node *nextSibling;
	DOM_NamedNodeMap *attributes;
	DOM_Document *ownerDocument;
	union {
		struct {
			DOM_DocumentType *doctype;
			DOM_Element *documentElement;
			DOM_String *version;
			DOM_String *encoding;
			int standalone;
		} Document;
		struct {
			DOM_NamedNodeMap *entities;
			DOM_NamedNodeMap *notations;
			DOM_String *publicId;
			DOM_String *systemId;
			DOM_String *internalSubset;
		} DocumentType;
		struct {
			int specified;
			DOM_Element *ownerElement;
		} Attr;
		struct {
			int length;
		} CharacterData;
		struct {
			DOM_String *publicId;
			DOM_String *systemId;
		} Notation;
		struct {
			DOM_String *publicId;
			DOM_String *systemId;
			DOM_String *notationName;
		} Entity;
		struct {
			DOM_String *target;
			DOM_String *data;
		} ProcessingInstruction;
	} u;
};