For most of the scenarios I can think of, parsing the dates out of strings that are in a standard format by convention will be much easier. The number of ways people will want to use qualifiers will increase like the number of properties and items. So the way I see it, we have to support string-based qualifiers at the minimum. Then I think we should only support strongly typed qualifiers if performance requires it. By setting an update polling frequency on templates that use the information I don't think we'll run into performance issues for most scenarios. Even with this example the qualifier type is a date range, not just a date. So do we want them to have to choose from a large, fixed list of qualifier types or just look at a similar example and set a string to something similar and then gradually enforce types on the most popular uses that we see. I think this type of organic growth as opposed to trying to guess the qualifier types in advance is exactly in the spirit of Wikipedia.