Class1: Employment Status says "The observation date may be collected instead of start date." but there is no description of what the "observation date" is or how it fits into the DAM (for example, is this a separate data element in Employment Status, or if it captured instead, how does a user of the data know which type of date was captured). Please better define this concept in the document. As well, if the observation data is captured (rather than a start date), what are the implications on the fact that it later says that "Employment status periods cannot overlap with start or end dates when these data are collected". If an observation data is captured instead of a true start date, are Employment Status  instances allowed to overlap?

Please clarify the usage of the observation date