gml:Node 

gml:Node represents the 0-dimensional primitive.
The optional coboundary of a node (gml:directedEdge) is a sequence of directed edges which are incident on this node. Edges emanating from this node appear in the node coboundary with a negative orientation. 
If provided, the aggregationType attribute shall have the value "sequence".
A node may optionally be realised by a 0-dimensional geometric primitive (gml:pointProperty).

Element Information

Model

gml:metaDataProperty* , gml:description{0,1} , gml:descriptionReference{0,1} , gml:identifier{0,1} , gml:name* , gml:container{0,1} , gml:directedEdge* , gml:pointProperty{0,1}
Children: gml:container, gml:description, gml:descriptionReference, gml:directedEdge, gml:identifier, gml:metaDataProperty, gml:name, gml:pointProperty

Attributes

QName Type Fixed Default Use Inheritable Annotation
aggregationType gml:AggregationType optional
gml:id ID required 
The attribute gml:id supports provision of a handle for the XML element representing a GML Object. Its use is mandatory for all GML objects. It is of XML type ID, so is constrained to be unique in the XML document within which it occurs.

Used By

Complex Types gml:DirectedNodePropertyType, gml:NodeOrEdgePropertyType, gml:NodePropertyType

Source 

<element name="Node" type="gml:NodeType" substitutionGroup="gml:AbstractTopoPrimitive">
  <annotation>
    <documentation>gml:Node represents the 0-dimensional primitive. The optional coboundary of a node (gml:directedEdge) is a sequence of directed edges which are incident on this node. Edges emanating from this node appear in the node coboundary with a negative orientation. If provided, the aggregationType attribute shall have the value "sequence". A node may optionally be realised by a 0-dimensional geometric primitive (gml:pointProperty).</documentation>
  </annotation>
</element>

Sample