NOTAM specifications (such as the Eurocontrol OPADD) use a specific set of terms in relation with the the applicability/validity of a NOTAM at a specific moment in time. The AIXM Temporality concept uses different terms. In particular, two AIXM temporality concept terms (“active” and "valid time") have a different meaning in AIXM as compared to their traditional NOTAM meaning. The diagrams to the right identifies these terminology differences.

• TimeSlice validity - in AIXM, each TimeSlice has a validTime, which indicates the time period (from date and time - until date and time) the information contained in the TimeSlice is applicable. In the OPADD terminology, this is equivalent to a NOTAM being “in force”. An Event also has a lifetime, which starts with the validTime.beginPosition of its “first” (according to the order on the timeline) TimeSlice and ends with the validTime.endPosition of its “last’ TimeSlice. 
•  active TimeSlice - The AIXM Temporality Concept version 1.1 defines an active TimeSlice as the “TimeSlice that has its beginPosition at or before the current system date/time and the endPosition after the current system date/time or an indeterminate endPosition”. In the diagram to the right, if the current time is T1, then the Event is not active, as none of its TimeSlices is active. The Event becomes active at the T2 moment in time and becomes inactive at T3.
• Events do not have schedules, therefore the concept of “active” NOTAM is not applicable directly to Events and the Event validTime is a continuous time period. The properties affected by the Event (such as closure times of a runway) might have an associated schedule.