There should be more consistency in the UML class diagrams
for each package. For example, attributes were shown for some classes,
and not for others.
There are also inconsistencies between the UML class diagrams and the
class descriptions.
There are no class descriptions for DV_CUSTOMARY_QUANTITY and
DV_GENERAL_TIME_SPECIFICATION. Although, there may not be much to those
classes, class descriptions should also be provided for consistency.
There are a few errors in the labelling of headers in class descriptions.
There should be more consistency in the presentation of the class
descriptions.
Fix errors in the invariants.