Figure 1.

States and transitions of the high-level sub-grammar. The different state types (see abbreviation in parenthesis) are explained in the text and are indicated by the different shapes. States of type bifurcate have a bifurcating transition leading both to a left (l) and a right (r) state. Any derivation tree of the grammar has to start in the begin state. The start states of the non-structural and structural sub-grammars simultaneously act as terminals for this high-level grammar and are depicted as double-edged octagons.