Signature sig_outside_foldrna is for the outside computation of RNA inputs, e.g. to compute McCaskill base-pair probabilities. The "normal" inside functions (defined in sigpart_basic.gap) need outside analogons, e.g. "bl" needs corresponding outside function "outside_bl".
A significant sub-set of the algebra functions used here is shared with signatures sig_foldrna.gap and sig_pknot_foldrna.gap. For re-usage, we moved those functions into a separate file (sigpart_basic.gap) and include the same file into the different signatures.