Core principle is temporal priority: believe the account
closer to the event
Thus privilege pINDRESP over
qJOBHIST where they refer to the same time
Initial requirements were for status histories
Conceptually less problematic
Easy to represent as month vectors: calendar files
But calendar orientation has drawbacks
Huge files, slow to process
Problematic to regenerate episodes, to reason about spells
while in calendar form
A poor representation of the sort of information we have
(state-changes attached to dates, spell-oriented), hence tend
to lose good left and right censoring info, gaps and so on.
A focus on spells, as in newpan, rather than
month-by-month calendars is logically better but slightly less
easy to manipulate
