Co-access allows members to register multiple records and DOIs for the same book content item. This option is provided to support members who publish book content on multiple platforms. A full overview of the service is provided on our website.  The following resources are available:

• Implementing Co-access
• How is Co-access determined?
• The Co-access interim page
• Identifying items in Co-access

Implementing Co-access

1. Sign up / Identify Co-access group participants
Publishers who wish to implement Co-access for their books must first establish which other Crossref members will participate in their Co-access group. Information about all participants must be supplied by the publisher (i.e content owner) or publisher's agent to our support team and will include:

• Names and prefixes of participating members
• Logo images for each participating member, formatted according to our image specifications

When all information has been provided we’ll set up the appropriate permissions on our end. Co-access status is determined at the member prefix level. This means when books with matching metadata are registered by members of a Co-access group, the book records will automatically be put into Co-access.

2. Register book content
Once permissions have been established you can register your book content. When a title is registered or updated we always check to see if that title exists in another record in our system. If it does, we’ll check to see if the title is registered  by a member of your Co-access group. If it has, we’ll complete your deposit and flag the book and chapter DOIs as being in Co-access in your submission logs. At this point, all DOIs matched in a Co-access cluster will resolve to the Co-access interim page.

If you're the first depositor in your Co-access group your title won’t be a Co-access title. Co-access is triggered only when multiple registrations exist for a single book title. This means your DOI(s) will resolve directly to your own registered landing page until a second DOI is registered by a member of your Co-access group.

3. Verify Co-access status
Co-access status will be noted in your submission logs for Co-access items. The log will also list the DOIs in Co-access with the DOI being registered or updated at the time of registration.

How is Co-access determined?

For a title to be placed in Co-access, the prefix of all DOIs in Co-access must be in a Co-access group. When book registration is attempted by a Co-access participant we check the ISBN of the book against book ISBNs in our titles database. If a title exists with that ISBN and is owned by a member of the submitters' Co-access group, the book record is registered and placed in Co-access with the existing book record(s). If a book is registered without an ISBN, we compare the book title against other book titles in our database.

Once a book has been placed into Co-access we compare titles of chapters submitted for the book and identify Co-access chapters as well.

If the metadata record submitted for a book is significantly different from other books in our database (distinct ISBNs), we aren't able to identify the book being registered as a new item and will create a new non-Co-access title.

Submission log

The Co-access status of a DOI is noted in the submission log sent to you when you register your content. Other DOIs in Co-access with the item being registered are noted as well.

<?xml version="1.0" encoding="UTF-8"?>
<doi_batch_diagnostic status="completed" sp="ds3.crossref.org">
<submission_id>1397117857</submission_id>
<batch_id>20161007151506957_10.2307/j.ctt7zvwrk</batch_id>
<record_diagnostic status="Success">
<doi>10.2307/j.ctt7zvwrk</doi>
<msg>Added with Co-Access</msg>
<dois_in_coaccess>
<doi>10.1515/9781400861477</doi>
<doi>10.1353/book.34426</doi>
</dois_in_coaccess>
</record_diagnostic>
<batch_data>
<record_count>1</record_count>
<success_count>1</success_count>
<warning_count>0</warning_count>
<failure_count>0</failure_count>
</batch_data>
</doi_batch_diagnostic>

The Co-access interim page

The DOI a user is resolving is highlighted on the interim page. The metadata provided on the interim page is pulled in from the deposited metadata of the highlighted item.

Identifying items in Co-access

All DOIs registered for a single book in Co-access will be included in the Books Depositor Report. The book will appear listed under each member that has created a co-access DOI for that specific book.

Co-access relationships between DOIs are identified via the relations expressed in the metadata record for each item.

In a JSON record from our REST API, the relation is expressed with the type “is-identical-to”
In this example, the record for DOI 10.2307/j.ctt13x0qhg contains 2 ‘is-identical-to’ relations:

http://api.crossref.org/works/10.2307/j.ctt13x0qhg

relation:
{
is-identical-to:
[
{
id-type: "doi",
id: "10.1353/book.38558",
asserted-by: "subject"
},
{
id-type: "doi",
id: "10.1515/9781400870004",
asserted-by: "subject"
}
]
}

In an UNIXSD XML record the relations are expressed as relations metadata:

<program name="relations" xmlns="http://www.crossref.org/relations.xsd">
  <related_item>
   <description>
     Co-Access
   </description>
   <intra_work_relation relationship-type="isIdenticalTo" identifier-type="doi" provider="Crossref">
     10.1353/book.38558
   </intra_work_relation>
  </related_item>
  <related_item>
   <description>
     Co-Access
   </description>
   <intra_work_relation relationship-type="isIdenticalTo" identifier-type="doi" provider="Crossref">
     10.1515/9781400870004
   </intra_work_relation>
  </related_item>
</program>