Currently additional patron attributes are always strings. It would be really useful to be able to specify what data type an additional attribute should be when it is created, like you can specify whether it has to be unique, or is repeatable. e.g. we might want it to be a DATE, or possibly a DATETIME, or we may indeed want a STRING, or an INT, or a DECIMAL etc - it really depends on what a given library is using the attributes for, and how they might want to run reports against it. This would be a more holistic way to deal with Bug 6339.