Generally coding is a concept of modeling reality with reduced effort but with physical copying.
Hence the result of coding is a reduction to the scope of representation as far as possible to be depicted with the chosen modeling technology. There will be never an escape, but choosing more than one model to serve more than one purpose. That led to various code derivatives, all of them using one basic reference code for ordering as e.g. with ICD-10 coding. However, concurrent depiction of several models in one image remains principally impossible.
Focusing a code on one purpose lets other purposes unsatisfied. This has to be taken into account when advertising for any coding concept. The operability of coding is generally bound to purpose. Inter-referring must be subject of evolutionary development, as code structures are subject of frequent change.[11]
Unambiguous coding requires strict restriction to hierarchical tree structures possibly enhanced with multiple links, but no parallel branching for contemporary coding whilst maintaining bijectivity.
