The key functionality of Crossmark is to allow researchers to easily determine when an article undergoes a status update. “Status updates” are defined as “changes that are likely to affect the crediting or interpretation of the work.” This means that things like spelling or formatting changes are not considered status updates, but “corrections, “retractions, “withdrawals” and other similar updates are considered “status updates”.
Typically, when a major update to a document occurs, the publisher will not modify the original document, but will instead issue a separate document (e.g. a correction/retraction notice) which explains the change. This separate document will have a different DOI to the document that it corrects and will, thus, contain different metadata.
In this example, “Article A” (with the DOI 10.5555/12345678) is eventually retracted by a Retraction Notice (with the DOI 10.5555/24242424x). Each article has Crossmark metadata, but the fact that the latter article updates the first article is only recorded in the later retraction’s Crossmark deposit. The Crossmark internal API has to tie the two documents together and indicate in the original document’s metadata, that it has been updated_by the second document.
Example 1: Simple Retraction
This is a simple example of Article A being retracted by a Retraction Notice where both A and its retraction notice have Crossmark metadata deposited.
First, the PDF is produced and the XML deposited to Crossref.
When the retraction is issued, it is issued as a separate “retraction notice” with its own DOI, PDF, Crossref metadata, etc.
- Retraction Notice of A Deposit XML
- Retraction Notice of A Landing Page
- Retraction Notice of A XMP
- Retraction Notice of A PDF
Example 2: Simple Correction
This is a simple example of Article B being corrected by a Correction Notice where both B and its correction notice have Crossmark metadata deposited. The only real difference between this and the previous example is that we are creating a different kind of “update.”
- Correction notice of article B Deposit XML
- Correction notice of article B Landing Page
- Correction notice of article B XMP
- Correction notice of article B PDF
Example 3: In-Situ Correction
When a publisher does not issue a separate update/correction/retraction notice and instead just make the change to the document in-place (without changing its DOI either), this is called an “in-situ update”. In-situ updates or corrections are not recommended because they tend to obscure the scholarly record. How do you tell what the differences are between what you downloaded and the update? How do you differentiate them when citing them (remember, we are only talking about “significant updates” here). Having said that, some publishers need to support in-situ updates and this is how they can be supported.
- Article D Deposit XML before correction issued
- Article D Deposit XML after correction issued
- Article D Landing Page
- Article D XMP generated before correction issued
- Article D XMP generated after correction issued
- Article D PDF generated before correction issued
- Article D PDF generated after correction issued
Example 4: Correction of article that has no Crossmark metadata deposited
If you deposit Crossmark metadata for a retraction or and update notice which, in turn, points at an article that does not have Crossmark metadata assigned to it, we will generate a “stub” Crossmark for the item being updated (e.g. being pointed to). The stub metadata will simply copy essential Crossmark metadata (crossmark_domains and domain_exclusive) out of the updating metadata. This metadata can be queried via the Crossref API, but obviously, it won’t activate anything on your site unless you add the Crossmark widget to the corresponding page of the item being updated.
- Article E Deposit XML (has no Crossmark metadata)
- Article E Landing Page (again, no Crossmark button, etc.)
- Article E XMP (none exists because it doesn’t have Crossmark metadata)
- Article E PDF (has no CrossMmrk logo or metadata)
Still, note that if you query Crossmark metadata for Article E, you will get a Crossmark stub which has been automatically been generated by CrossRef.
The procedure for the updating content is normal
- Correction of Article E Deposit XML
- Correction of Article E Landing Page
- Correction of Article E XMP
- Correction of Article E PDF
Example 5: Correction notice that corrected multiple documents
Sometimes publishers issue correction/clarification notices which might provide corrections for multiple documents. This too can be supported by Crossmark. In the following example, one correction/clarification document provides updates to two documents (F & G)
- Correction Notice of F and G Deposit XML
- Correction Notice of F & G Landing Page
- Correction Notice of F and G XMP
- Correction Notice of F and G PDF
Here are a few answers to technical questions that might help too!
- What happens if certain values are not included in the deposited Crossmark metadata, for example the value for the @order attribute?
- Optional attributes are optional. In the case of @order, if it is absent, then it will return stuff in the order you list it in deposit- but this is not guaranteed. If you want to be *sure* of the order, then you can use @order. A fairly detailed description of the Crossmark deposit elements (including what is optional) in the schema itself.http://www.crossref.org/schema/documentation/4.3.2/4_3_2.html#crossmark