N2T.net can be seen as a kind of URL shortener-plus-hardener in the sense that URLs such as
https://n2t.net/pdb:2gc4 https://n2t.net/taxon:9606 https://n2t.net/ark:/47881/m6g15z54
made possible by N2T are shorter and stabler than their non-N2T counterpart URLs:
http://www.rcsb.org/pdb/explore/explore.do?structureId=2gc4 http://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?mode=Info&id=9606 http://bibnum.univ-lyon1.fr/nuxeo/nxfile/default/49e1576c-0cae-4b4b-a63b-73370f476681/blobholder:0/THm_2014_NGUYEN_Marie_France.pdf
These are examples of "compact identifiers", a term that arose from a cooperative agreement between the Identifiers.org resolver and N2T.net to serve a common set of over 600 identifier schemes (or prefixes).
A scheme is represented by the characters after "n2t.net/" and before the colon, which, in the examples, are pdb, taxon, and ark. This work and our plans to reach out to publishers to encourage adoption of inline citation of compact identifiers is described in Uniform Resolution of Compact Identifiers for Biomedical Data.