We are writing the document instances of each of these DTDs in such a way that they can exist as standalone documents. A typical biography document is some 1500-2500 words of prose, with major subdivisions for key aspects of the writer's life such as birth, family, political activities etc. The biography and writing documents are structured to include embedded chronological events that may be extracted into the project's larger chronology. These structures of course give us the ability to merge the dates and chronology material from a variety of documents. In reality, however, this is not as simple as it may sound.
Dates are one major problem area.
We have had to structure and tag our dates to facilitate their inclusion in the larger chronology and to find ways of dealing with events where the date is not known or unclear. For example, events such as book publications for which we know only a year and no month or day are initially clustered together at the beginning of each year. Listed in this way, they seem unpolished to the user, and much less useful than the more exactly dated publication events which are placed with greater precision in relation to the surrounding events. Moreover, in some cases, year-only events appear before events which are known from other evidence to precede them. Or a researcher into religion may find that the first Anglican nursing order, the Sisters of St John the Divine, was founded on a particular day.