The iso-date attribute on the activity-date tag is optional.
This is the only machine-readable section of the activity dates.
There are some activities that do not have precise dates because e.g. they are still in the pipeline/identification stage.
Activity dates cannot be read and used by applications unless there is an iso-date attribute.
Make the iso-date attribute mandatory.
make the iso-date attribute fuzzy (perhaps you could just put “2012” rather than “2012-01-01” - I think that would still be ISO-compliant)
add an attribute to define the precision of the date (e.g. “precision”, for which the values could be year, month, day)