Instance identifier

SYNTAX:
instance_id = '#' simple_id .
Data structures consisting of one or more related entity instances can be specified in a EDMexpressX^ mapping schema. All these instances must be defined by an ENTITY definition in the Target Schema. Each of these instances is given a unique name so that they can be referenced from other constructs in the mapping schema.
The name associated with an entity instance is an identifier of type instance_id. An instance_id must begin with the character '#' followed by a simple_id.
 #startPoint = tar::POINT(0.0,0.0);
 #endPoint  = tar::POINT(100.0,0.0);
 #myLine   = tar::LINE(#startPoint,#endPoint );