How do I search titles that have been linked to a given class mark ?

If you know the class mark itself, use the Find command when in the Titles file and type in the field Shelf mark the class mark. For instance : 345

If you know only the class mark definition, display the Class marks file and choose the Find command. Type in the definition. Once the class marks have been found, activate it (them), then click on the “link” icon near the Titles word in the favorites bar. You get the titles classified under this class mark.