We are using the Elemental sketcher from Dotmatics (https://www.dotmatics.com/) to allow structure search within WebCSD v2 and this communicates with our CSD search engine via a SMARTS substructure representation. Occasionally, the translation from a SMARTS substructure to the equivalent substructure in the CSD is not completely straightforward. If you would like to learn more about SMARTS or visualise SMARTS patterns, the web application SMARTSviewer by the University of Hamburg is an excellent reference. The new CSD Sketcher currently also uses a SMARTS substructure query, however the queries generated via the two Sketchers are not identical potentially leading to a different search result in some cases.
If you have any questions or concerns about your search results, please do contact us through CCDC support. We are very happy to help out if you would like some guidance on sketching or defining queries in WebCSD v2.