This function generates the following time fields:
'TIME' is the time in hours relative to the subject's first record, be it an administration or observation event.
'TAFD' is the time in hours relative to the subject's first administration of the respective parent. Note that if a subject has received multiple drugs (parents), the 'TAFD' field refers to the respective first administration.
'TAD' is the time in hours relative to the most recent administration of the parent compound.