I've updated DSSR to beta-r11-on-20130603 which contains a new option --long-idstr to delineate fields of nucleotide id string. The format is:
model-number.chain-id.nucleotide-name.nt-sequence-number.insertion-code
It has five fields, and some of them (model number, insertion code) can be missing. For example, with the new option, B.U31/16 in 1d9h would become .B.U31.16..
I believe this DSSR update would fulfill your needs -- please verify and report back how it goes.
Xiang-Jun
Updated on 2013-06-18: the new format is:
model-number.seqid.chain-id.nt-name.nt-number.insertion-code