Two specs are defining error reports for the CSW services:

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(1) CSW-ebRIM Registry Service - Part 1: ebRIM profile of CSW: OGC 07-110r2

7.9.2 Fault handling
In the event that an exception report is produced for any reason, a single SOAP Fault element information item shall be included as the only child element information item of the SOAP body element (see SOAP12, sec. 5.4). The elements of the SOAP Fault are constructed as follows:
a) env:Code/env:Value = ―env:Sender‖ or ―env:Receiver‖, depending on the source of the error and the HTTP status code (i.e., 4xx, 5xx);
OGC 07-110r2
Copyright © 2008 Open Geospatial Consortium, Inc. All Rights Reserved. 15
b) env:Code/env:Subcode/env:Value = value of ows:Exception[1]/@exceptionCode (an OWS exception code value shall be prepended with ―ows:‖);
c) env:Reason/env:Text = ows:Exception[1]/ows:ExceptionText[1], where @xml:lang = ows:ExceptionReport/@language;
d) env:Detail contains the original ows:ExceptionReport element
NOTE The ―env‖ prefix maps to the namespace URI ―http://www.w3.org/2003/05/soap-envelope‖.



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(2) OGC® Cataloguing of ISO Metadata (CIM) Using the ebRIM profile of CS-W
Reference number of this OGC® document: OGC 07-038

8.2.4 Error handling
The statements expressed in clause 7 of the OGC Catalogue Services – ebRIM (ISO/TS 15000-3) profile of CS-W [OGC 05-025] relatively to exception reports are applicable.

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(3)