Assessment Period End Dates in relation to 1095C reporting

In the Q & A from the Advisor Webinar: EBS HCM Updates for Employer Shared Responsibility Reporting it is indicated that the Assessment Period End Dates for new hires in the pat year (those that did not complete an assessment prior to 1/1/2015) need to have the

Assessment Period End Date populated.  Can you provide more details on how this data is being used to populate fields on the 1095C?  What fields? What values are derived?  Also, does this need to be populated for all employees or just those with an initial assessment of being ACA full-time?