HathiTrust Overlap Reports

In order to assist members in evaluating the utility of the Emergency Temporary Access Service, HathiTrust can provide reports indicating which items included in your most recent print holdings submission would be available through the service.

Information on how to add ETAS records to your local catalog is available on our website. See below for details on receiving your overlap report, troubleshooting matching issues or updating your holdings.


As with most other HathiTrust operations, overlap is determined by matching the OCLC Control Numbers (OCNs) in your print holdings to the OCNs in the bibliographic records for the items in our digital collection.

Report Structure

Reports are provided as tab-delimited text files (.tsv) and include all of the print holdings we received in your most recent submission.  Reports include the following fields:

Overlap Report Fields
Field Name Description Notes
oclc OCLC control number As provided in your print holdings
local_id Local identifier Either your local_system_id or local_item_id, whichever you provided to us in your print holdings
item_type Possible values: *mono* (for single-part monographs) *multi* (for multi-part monographs) *serial* (for serials) Note that our system overwrites member-provided values in this field for multi-part monographs only, if the matching bibliographic record from our collection has a value of item_type=”multi” for the same OCN.
rights Indicates the rights status of the item, according to our standard rights determination process Possible values: *ic* (in-copyright) *pd* (public domain) *und* (undetermined; treated as ic for access purposes)
access Indicates whether access to the item is permitted under normal operating conditions Possible values: *allow* (full view) *deny* (limited view)

In the example below, this library, via the Emergency Temporary Access Service, would now have access to every item shown whereas before only one item – OCLC number 5577640, row 2 – was available via HathiTrust.    See the full list of codes.

Overlap Report Example
oclc local _id item_type rights access
1234380 99467233402401 serial ic deny
5577640 994021423402401 multi pd allow
30688167 994628483402401 multi ic deny
5040497 993390943402401 serial ic deny

In this example, there are four items (OCLC numbers 2698, 2867, 2950 and 23523324)  that HathiTrust does not have or can not match to your record (i.e., the “access” value is blank), and two that were not viewable before (“deny”) and now are temporarily available under the ETA service (OCLC numbers 2747 and 2635), and one (OCLC number 3014) that was previously viewable and remains so (“allow”).

Records with values in the “access” and “rights” columns were successfully matched to something in our digital collection. Records with no values in these fields could not be matched to anything in our collection.

Values in the “access” and “rights” columns are derived from our holdings database, so they reflect the access determinations that would apply under normal (non-ETAS) conditions. Under those normal conditions, your users have access only to the “allow” records.

If your library is approved for ETAS, your users will have access to both the “allow” and the “deny” records for the duration of the service.

Matching Issues

Access to materials through the HathiTrust Emergency Temporary Access Service (ETAS) is limited to items held in your library’s physical collection, which is based on the information in your most recent print holdings submission to HathiTrust. If an item in your physical collection is not available via ETAS, it’s likely that we could not identify the corresponding item in our digital repository. This usually occurs when the OCLC control number for the item in your print holdings does not match the number in our bibliographic record for the item. To check this:

  1. Find the OCLC number for the item in your local catalog.
  2. Open your library’s latest ETAS overlap report. This report is shared with your institution’s designated ETAS contact; please reach out to them for access to the report.
  3. Search for the OCLC number in the overlap report
  • If the row for that OCLC number contains the value “allow” in the ACCESS column, this means you have full-view access to the item all the time (including under normal, non-pandemic or ETAS circumstances)
  • If the row contains the value “deny” in the ACCESS column, this means the item is only available to your users via ETAS, and only when logged in to HathiTrust.
  • If the row has a blank value in the ACCESS column, we were unable to match the item to anything in our collection. Either the item was not reported to us in your print holdings, it was reported with an OCLC number that we could not match to anything in our records, or for multipart items like series or journals we may not be able to match to the exact volume or part depending on cataloging practices at your institution.

HathiTrust cannot update individual records to enable ETAS access. To fix scenario 3c above, you may update your print holdings so that the OCLC number in your record matches the OCLC number in our record, or the volume information to match the HathiTrust record’s volume information. We cannot accept incremental print holdings updates, so you will need to regenerate and resubmit your entire holdings.

Accessing Your Overlap Report

Please contact support@hathitrust.org to request your library’s overlap report.