282 CHAPTER 9 Rule statement templates and subtemplates 9.3.2.6 Temporal data constraints A temporal data constraint constrains one or more temporal data items (data items that represent time points or time periods). There are six subcategories of temporal data rule, each with its own template(s): 1. simple temporal data constraints, which require that particular dates or times fall within a certain temporal range: these are simply range rules, as described in Section 9.3.2.6.1; 2. temporal data non-overlap constraints, which require that the time periods specified in sets of records do not overlap each other, described in Section 9.3.2.6.2; 3. temporal data completeness constraints, which require that the time periods specified in a set of records are contiguous and between them completely span some other time period, described in Section 9.3.2.6.3; 4. temporal data inclusion constraints, which require that the time periods specified in a set of records do not fall outside some other time period, described in Section 9.3.2.6.4; 5. temporal single record constraints, which require that a temporal state of affairs be recorded using a single record rather than multiple records: these are simply uniqueness constraints, as described in Section 9.3.2.6.5; 6. day type constraints, which restrict a date to one or more days of the week or a particular type of day such as a working day (typically but not necessarily any day other than a Saturday, Sunday, or