<respStmt>s in the header, we often need to specify the date or period for which someone had a specific responsibility (for example, they might have been transcribing the text in from 2012 to 2013, then someone else took over from 2013; or they might have been project manager for a specific period). This can be done by adding a
<date> element inside
<resp>, but it would be much cleaner if
<resp> where a member of att.datable.