Dear Hans I agree with you, results of your volunteering to add new bond types and types of arrows should be added to chem now, where possible including the corresponding documentation. The adjustment of bond length of labeled bonds better is a separate issue, which could be implemented subsequently.
If someone wants to help here, this issue refers to IUPAC rule GF-2.1.5 "Positioning of atom labels" of IUPAC's recommendations "Graphical Representation Standards for Chemical Structure Diagrams" as compiled by Jonathan Brecher in Pure Appl. Chem. 80(2), 277-410, 2008 (doi:10.1351/pac200880020277, published by open access), page 305, reading > In all cases, not only should the bonds point to the center of a letter or > entire element symbol, but the label should be positioned with that center > coincident with the location where the bond would have ended if the atom was > not labeled. As a result, the visible portion of a bond to a labeled atom will > be shorter in the diagram than the visible portion of a similar bond to an > unlabeled atom. Best regards, Norwid
