
43Central Concepts
at zero upon a fracture occurring and then would increase until the next
fracture occurs; and the start of treatment would be recorded in its own on
treatment attribute (along with details of the type, of treatment, its dose, etc.)
and would modify other attributes such as the decrease in bone mineral density.
Regardless of the frequency and pattern of changes required to maintain the
values of attributes, a DES can manage this.
Sometimes a specic value needs to be stored unchanged because that
information is important either for subsequent calculations (e.g., the value of
glycosylated hemoglobin at the time of calculating ...