Syntactical and Logical Constructs in GDL

GDL distinguishes between the constructs that are literally defined by entries in the GDL source file and the representation of those constructs in GDL's internal data. The former is a syntactical representation, and the latter is a logical representation. The representations differ when constructs are defined in the source file. The GDL parser creates only one logical representation of a construct for a given construct type and construct tag, no matter how many times such a construct is defined in the GDL source file.