4.17 Annex Libraries and Annex Subclauses
The SAE AADL standard supports extension of the core language through annex library declarations and annex subclauses for different annex sublanguages.  These are represented by the abstract classes AnnexLibrary (shown in Figure 32) and AnnexSubclause (shown in Figure 15).  These classes are subclasses of NamedElement with the annex name recorded in the name attribute. 
These classes have concrete subclasses DefaultAnnexLibrary and DefaultAnnexSubclause. Those default classes record the content of an annex library or annex subclause declaration as a string.  This allows annex sublanguage expression to be preserved without parsing them.
If an annex sublanguage is introduced as a meta model extension in the form of an Ecore package, then the root expression of the sublanguage is introduced as a new subclass of AnnexLibrary and AnnexSubclause.  In this case, a sublanguage parser can convert the sublanguage text into an object representation that is a natural extension of the core AADL object model.