This is an example of a Research and Advisory Services patent investigation for Markush claims.

Our chemistry analysts are well-versed in researching chemical structures and substructures that exist in the technical and patent literature, including
the Markush claims. Using such search tools as the CAS RegistrySM and MARPAT™ databases in STN™, Nerac analysts are able to research worldwide publications including over 60 international patent authorities for publications that incorporate chemical structures.