"Grammars/gra_overdangle.gap" essentially is a copy of Grammars/gra_nodangle.gap, but we want to keep names clear. The difference stems from different MFE or partition function algebras, not different grammars. And those differences are realized by overloading the few according functions in the main GAP-L file ("overdangle.gap"), not by different algebra files.
Following an idea from splitting the Signature Signatures/sig_foldrna.gap, large parts of commonly used production rules are outsourced into the grammar part file Grammars/Parts/grapart_basic.gap.