What are common/current practices wrt Link application to fragments?

[zimeon]

What are common/current practices wrt Link application to fragments? In the PLOS case of an image with a DOI that resolves to a point in an HTML page for the paper (e.g. http://doi.org/10.1371/journal.pone.0118554.g001 ->
http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0118554#pone-0118554-g001) I think one can use the anchor="#frag" attribute in the Link element (https://tools.ietf.org/html/rfc5988#section-5.2) to set the context/subject to be other than the current document. But is the commonly done?

[zimeon]

Input for Geoffrey Bilder: very few publishers assign DOIs to components and that, of them, a tiny fraction link to fragments with the HTML page. Sampling a bunch of components (http://api.crossref.org/types/component/works?sample=100) a few times seems to confirm this. It also shows the IUCR cases where they link directly to data, software, etc.

After running tests on a sample of about 4000 DOIs for component works (out of 1769921 in CrossRef) I found DOIs from 3 out of 26 publishers that resolve to URIs with fragments. Examples from each publisher are:

http://doi.org/10.7717/peerj.305/table-1 -> https://peerj.com/articles/305/#table-1
http://doi.org/10.1172/jci37581ds1 -> http://www.jci.org/articles/view/37581#sd
http://doi.org/10.12952/journal.elementa.000038.t005 -> http://elementascience.org:80/article/info:doi/10.12952/journal.elementa.000038#elementa-000038-t005