It is also unclear how to specify this extract from a much larger standard, and since it is presented as an XML notation, other serialisations would need to be specified separately in any case. DCMI Period identifies a single time interval . For multiple disjoint intervals, repeated instances of DCMI Period may be used. DCMI Period is unsuited for identification of recurring and periodic time intervals. Identifying a time interval - the DCMI Period scheme We identify a time interval by specifying the start and end of the interval.
All components are optional.
If either start or end is absent, then this implies an interval unbounded on that side. In this context the name is non-normative. In the case of a conflict, the interval identified by the start and end values takes precedence. The name is provided for user convenience only. The components of a DCMI Period identifier have no meaning when disaggregated, since in any particular instance it is the complete set which acts as the identifier .