1. There are no gaps between elements. The instant one element ends, the next element begins. A subject spends no time “between” elements.
  2. The ELEMENT (Description of the Element) variable usually indicates the product being administered during an element, or, if no product is being administered, the other activities that are the purpose of this period of time (e.g., "Screening", "Follow-up", "Washout"). In some cases, this time period may be quite passive (e.g., "Rest"; "Wait, for disease episode").
  3. The TESTRL (Rule for Start of Element) variable identifies the event that marks the transition into this element. For elements that involve product, this is the start of product administration.
  4. For elements that do not involve product, TESTRL can be more difficult to define. For washout and follow-up elements, which always follow product exposure elements, the start of the element may be defined relative to the end of a preceding product administration. For example, a washout period might be defined as starting 24 or 48 hours after the last dose of product for the preceding product exposure element or epoch. This definition is not totally independent of the TA dataset, because it relies on knowing where in the study/trial design the element is used, and that it always follows a product exposure element. Defining a clear starting point for the start of a non-product exposure element that always follows another non-product exposure element can be particularly difficult. The transition may be defined by a decision-making activity such as enrollment or randomization. For example, every arm of a study/trial that involves treating disease episodes might start with a screening element followed by an element that consists of waiting until a disease episode occurs. The activity that marks the beginning of the wait element might be randomization.
  5. TESTRL for a product exposure element may be thought of as “active” whereas the start rule for a non-product exposure element—particularly a follow-up or washout element—may be “passive.” The start of a product exposure element will not occur until a dose is given, no matter how long that dose is delayed. Once the last dose is given, the start of a subsequent non-product exposure element is inevitable, as long as another dose is not given.
  6. Note that the date/time of the event described in TESTRL will be used to populate the date/times in the Subject Elements (SE) dataset, so the date/time of the event should be captured in the CRF.
  7. Specifying TESTRL for an element that serves the first element of an arm in the TA dataset involves defining the start of the study/trial. In the examples in this document, obtaining informed consent has been used as "Trial Entry."
  8. TESTRL should be expressed without referring to arm. If the element appears in more than 1 arm in the TA dataset, then the element description (ELEMENT) must not refer to any arms.
  9. TESTRL should be expressed without referring to epoch. If the element appears in more than 1 epoch in the TA dataset, then the Element description (ELEMENT) must not refer to any epochs.
  10. For a blinded study/trial, it is useful to describe TESTRL in terms that separate the properties of the event that are visible to blinded participants from the properties that are visible only to those who are unblinded. For product exposure elements in blinded studies/trials, wording such as the following is suitable: "First dose of study product for an exposure epoch, where study product is X."
  11. Element end rules are rather different from element start rules. The actual end of one element is the beginning of the next element. Thus, the element end rule does not give the conditions under which an element does end, but the conditions under which it should end or is planned to end.
  12. At least 1 of TEENRL and TEDUR must be populated. Both may be populated.
  13. TEENRL describes the circumstances under which a subject should leave this element. Element end rules may depend on a variety of conditions. The TA dataset, not the TE dataset, describes where the subject moves next, so TEENRL must be expressed without referring to arm.
  14. TEDUR serves the same purpose as TEENRL for the special (but very common) case of an element with a fixed duration. TEDUR is expressed in ISO 8601. For example, a TEDUR value of P6W is equivalent to a TEENRL of "6 weeks after the start of the element."
  15. Note that elements that have different start and end rules are different elements and must have different values of ELEMENT and ETCD. For instance, elements that involve the same product but have different durations are different elements. The same applies to non-product exposure elements. For instance, a washout with a fixed duration of 14 days is different from a washout that is to end after 7 days if product cannot be detected in a blood sample, or after 14 days otherwise.