DBDOC shows you all the data used in your graphics. It also allows you to see the taglists in parallel with the Composer and WinCAD ones. This makes the task of keeping the databases synchronized easy.
DBDOC error checking tells you about the tags in your database that are not in any graphic, about tags that no longer exist in the database and tags that no longer have source blocks in the configuration. This information allows you to keep your graphics very tidy.
DBDOC gives you a direct link from the TenoreNT graphic to the configuration CLD / CAD files, making fault-finding trivial.