metadata, DOI and crossRef 2.0 (2017)

Intro

Metadata Search is our primary user interface for searching and filtering of our metadata. It allows users to quickly enter any term and users can search and filter on a number of elements, including ISSN, ORCIDs, funding data and more. It can be used to lookup the DOI for a reference or a partial reference or a set of references.
https://www.crossref.org/services/metadata-delivery/

In order to encourage publishers and other content producers to embed metadata into their PDFs, we have released an experimental tool called “pdfmark”, This open source tool allows you to add XMP metadata to a PDF. What’s really cool, is that if you give the tool a Crossref DOI, it will lookup the metadata in Crossref and then apply said metadata to the PDF. More detail can be found on the pdfmark page on the Crossref Labs site. The usual weasels words and excuses about “experiments” apply.
dec 2009
https://www.crossref.org/blog/add-crossref-metadata-to-pdfs-using-xmp/

Using Crossref metadata to enable auditing of conformance to funder mandates: A Guide for publishers
Funders are increasingly setting mandates around publications that result from research they have funded. The mandates include specifications about licenses, embargoes, and notifications of publication acceptance and/or publication. This poses logistical problems for all the parties involved. Funders will need a way to track outputs from thousands of publishers. Publishers will need a standard and efficient way to demonstrate conformance to the mandates. All the stakeholders in the process (funders, publishers, institutions and researchers) will span disciplines, institutions, geographies and jurisdictions. Crossref was setup specifically to deal with these sorts of multiple bilateral relationships.

Crossref has extended its metadata schemas and Application Programming Interfaces (APIs) to enable funding agencies, institutions and publishers to use Crossref as a metadata source that can be used to track research that is subject to these mandates and to ensure that said research is being disseminated according to the requirements of the mandates.

https://data.crossref.org/schemas/

Ref.
https://github.com/CrossRef/rest-api-doc/blob/master/funder_kpi_metadata_best_practice.md

60 ref in
https://www.crossref.org/categories/metadata/

Get ready for Crossmark 2.0

 Publishers can upgrade to the new and improved Crossmark 2.0 including a mobile-friendly pop-up box and new button. We will provide a new snippet of code for your landing pages, and we’ll support version v1.5 until March 2017.
We recently revealed a new look for the Crossmark box, bringing it up-to-date in design and offering extra space for more metadata. The new box pulls all of a publication’s Crossmark metadata into the same space, so readers no longer have to click between tabs. 
Linked Clinical Trials and author names (including ORCID iDs) now have their own sections alongside funding information and licenses.

https://www.crossref.org/blog/get-ready-for-crossmark-2.0/

https://www.crossref.org/blog/crossref-to-auto-update-orcid-records/

This is a summary of the technical and production steps that a publisher will need to follow to participate in CrossMark.
Sign up

Drop an email to crossmark_info@crossref.org to let us know that you want to get started with CrossMark. CrossMark fees are activated when you start to deposit, and are US$0.20 for current content, $0.02 for back file (older than two years)

CrossMark metadata should be deposited as part of a regular CrossRef DOI deposit, but can also be deposited as stand-alone data to help publishers populate their backfiles.

Record the DOI in HTML metadata

The publisher should ensure that the DOI is embedded in the HTML metadata for all content to which CrossMark buttons are being applied as follows:

<meta name=”dc.identifier” content=”doi:10.5555/12345678” />

http://crossmarksupport.crossref.org/technical-implementation-guidelines/

DOI

Over 20,000 DOI name prefixes within the DOI System
Over 5 billion DOI resolutions per year

Relation to other schemes

Strong focus on interoperability and on working with existing and new schemes; technical, syntactic, and semantic interoperability

http://www.doi.org/factsheets/DOIKeyFacts.html