The issue arises when there is a "?" in the dates in a subject field. I'm told by one of our catalogers that this is the correct way according to LOC to catalog an uncertain date in a subject heading. The problem is that when the "?" is part of the date, it breaks the subject linking. Two examples: 1. Incorrect subject heading, linking works: Thomas, à Becket, Saint, 1118-1170 2. Correct subject heading, linking does not work: Thomas, à Becket, Saint, 1118?-1170