These are the steps publishers need to take to get started with Crossmark:
1. Sign up
Drop an email to email@example.com to let us know that you want to participate in Crossmark. There is no annual service fee for Crossmark, but up to the end of 2019 there were fees for each record that was updated or corrected, and these were included in the quarterly content registration invoices. From January 2020 onwards these fees have been removed, so the last time members will see these fees will be on their Q4 2019 content registration invoice.
2. Create a Crossmark Policy Page and assign it a DOI
Create a page on your website explaining that you are participating in the Crossmark service and have committed to maintaining version of record copies of content that display the Crossmark button. This page should have a DOI to enable persistent linking. This page should also explain your policies on corrections, retractions, withdrawals and other updates, and contain definitions and explanations of any additional custom metadata fields that are being used. The page may also include links to other relevant policies such as author submission guidelines, peer review guidelines, etc.
3. Deposit Crossmark metadata
Crossmark metadata should be deposited as part of a regular Crossref DOI deposit, but can also be deposited as stand-alone data to help populate backfiles.
For Crossmark-only deposits, the schema and schema documentation related to resource-only deposits can be found here:
The minimum required Crossmark metadata comprises:
- The DOI of the content the Crossmark is being applied to
- The DOI for your Crossmark Policy Page
- The DOI of any piece of content that is being updated
4. Provide DOIs for items being corrected or updated
Crossmark “updates” should only be deposited for changes that are likely to effect “the interpretation or crediting of the work.” In other words, updates should only be deposited for editorially significant changes. Updates should not be deposited for minor changes such as spelling corrections, formatting changes, etc.
There are 12 defined types of accepted “update” within Crossmark. The values for these are:
If an update does not fall into one of these categories it should instead be placed in the "more information" section of the pop-up box by being deposited as an assertion.
When deposited content corrects or updates earlier content the DOI(s) of the corrected content must be supplied in the Crossmark metadata. See the Crossref unixref documentation section on “updates” for examples of how this is recorded in the Crossmark metadata.
When a correction is made in situ (i.e. replaces the earlier version completely), then the DOI of the corrected content will be the same as the DOI for the original Crossref deposit.
5. Record the DOI in HTML metadata
You should ensure that the DOI is embedded in the head of the HTML metadata for all content to which Crossmark buttons are being applied as follows:
<meta name=”dc.identifier” content=”doi:10.5555/12345678” />
6. Apply the CrossMark button to your HTML pages
- v2.0 is the current version. This update brings a responsive Crossmark box and new button designs. The v2.0 snippet can be seen below, and more detail on how to upgrade to this version is on the CrossMark v2.0 page.
<!-- Start CrossMark Snippet v2.0 --> <script src="https://crossmark-cdn.crossref.org/widget/v2.0/widget.js"></script> <a data-target="crossmark"><img src="https://crossmark-cdn.crossref.org/widget/v2.0/logos/crossmark-logo-rectangle.svg" width="150" /></a> <!-- End CrossMark Snippet -->
- v1.5 will be supported until March 2017. This implements HTTPS, and can be used both on HTTP and HTTPS sites. You should always access the widget files with HTTPS even if your site is HTTP.
- v1.4 and lower are now deprecated. This and older versions of the widget will continue to work, but we recommend that you use the most recent version.
Changing the button in the Widget
You can change the Crossmark button that is used simply by changing the “src” attribute of the “img” element to point to one of the following:
The button can be re-sized according to your design needs by changing the image width in the image tag
Please follow these guidelines on the use of Crossmark buttons.
7. Apply Crossmark button and metadata to PDF content
Add Crossmark metadata to PDF content
Crossref has created an open source tool called “pdfmark” for embedding metadata in PDF files. Minimally, this metadata must include the DOI of the content and the optional Crossmark domain(s).
So, the appropriate metadata was added to the above PDF with the following command:
java -jar pdfmark.jar -d 10.5555/12345678 sample_crossmark_article_pdf_w_crossmark.pdf
A minimal XMP file for the above PDF would look like this:
<?xml version="1.0" encoding="UTF-8"?> <?xpacket begin="?" id="W5M0MpCehiHzreSzNTczkc9d"?> <x:xmpmeta xmlns:x="adobe:ns:meta/" x:xmptk="Adobe XMP Core 4.0-c316 44.253921, Sun Oct 01 2006 17:14:39"> <rdf:RDF xmlns:rdf = "http://www.w3.org/1999/02/22-rdf-syntax-ns#" xmlns:pdfx = "http://ns.adobe.com/pdfx/1.3/" xmlns:pdfaid = "http://www.aiim.org/pdfa/ns/id/" xmlns:xap = "http://ns.adobe.com/xap/1.0/" xmlns:xapRights = "http://ns.adobe.com/xap/1.0/rights/" xmlns:dc = "http://purl.org/dc/elements/1.1/" xmlns:dcterms = "http://purl.org/dc/terms/" xmlns:prism = "http://prismstandard.org/namespaces/basic/2.0/" xmlns:crossmark = "http://crossref.org/crossmark/2.0/"> <rdf:Description rdf:about=""> <dc:identifier>doi:10.5555/12345678</dc:identifier> <prism:doi>10.5555/12345678</prism:doi> <prism:url>http://dx.doi.org/10.5555/12345678</prism:url> <crossmark:MajorVersionDate>2015-08-14</crossmark:MajorVersionDate> <crossmark:DOI>10.5555/12345678</crossmark:DOI> <pdfx:doi>10.5555/12345678</pdfx:doi> <pdfx:CrossmarkMajorVersionDate>2015-08-14</pdfx:CrossmarkMajorVersionDate> </rdf:Description> </rdf:RDF> </x:xmpmeta> <?xpacket end="w"?>
Note: It may appear redundant to apply Crossmark elements both in their own ‘Crossmark’ namespace as well in the ‘‘pdfx’ namespace, but the latter is necessary to ensure the Crossmark elements appear in the PDF dictionary, a specific requirement for some search engines. PDF mark was updated in May 2012 to include metadata in a PDF’s document information dictionary, again to account for search engine requirements. Any metadata found in the pdfx namespace will be copied over to the document info dictionary. Simply make sure that Crossmark metadata is in the pdfx namespace in the XMP provided to the tool.
Apply linked Crossmark buttons to PDF content
.eps files of each of the Crossmark buttons can be found below.
Crossref has created “pdfstamp”, an open-source command line tool that makes it possible to add an image or “stamp” to any location on a PDF and to link that image to a chosen URL.
The link structure for Crossmark links from PDFs looks like this:
The doi argument is pretty self-explanatory.
The domain argument tells the Crossmark system what kind of static content the link is coming from. This will change for different static formats (e.g. epub, etc.)
The date_stamp argument tells the Crossmark system the date on which a last “Major Version” of the PDF was generated. In the vast majority of the cases, this will just be the date on which the article was published. However, in cases where a publisher makes significant corrections to a PDF in-situ (they do not issue a separate correction or new version of the document with a new DOI) then the date_stamp should reflect when the PDF was regenerated with the corrections. The system will then use the date_stamp in order to tell whether the researcher needs to be alerted to updates or not. The date_stamp argument should be recorded in the form yyyy-mm-dd. (ISO 8601)