att.duration.iso provides attributes for recording normalized temporal durations. [3.6.4. Dates and Times 13.4. Dates]
Membersatt.duration [att.timed [annotationBlock binaryObject ellipsis gap media] date time]
dur-iso(duration) indicates the length of this element in time.
Status Optional
Datatype teidata.duration.iso

If both when and dur or dur-iso are specified, the values should be interpreted as indicating a span of time by its starting time (or date) and duration. In order to represent a time range by a duration and its ending time the when-iso attribute must be used.

In providing a ‘regularized’ form, no claim is made that the form in the source text is incorrect; the regularized form is simply that chosen as the main form for purposes of unifying variant forms under a single heading.