At the moment the index on Record control-number (7xx$w, 8xx$w) includes the $w subfields of multiple linking fields. This means that we can't specify a search that only find a specific type of link. Example: * Finding all volumes linked to a set record, will also find records that are also linked as another physical form (776) or a preceding entry (780) It would be nice to have the general, but also more specific indexes limited to the relevant $w only. As features like bug 26314 use the indexes in internal functions to do searches in the background, we cannot easily solve this with local changes to indexing and XSLT.