ValidDuration describes a duration indicating for how long the measurement is valid starting with its measurement time. The record must only be used for the time frame in which it is valid. The generation of records should be performed in such a way, that gaps should not occur. Note that a record can be “nullified” if a newer record is manifested, i.e. the most recent information should be used.
• The ValidDuration field MUST be present in the record.
• The ValidDuration field type MUST be an ISO duration.
• The value of ValidDuration SHOULD be in the order of the time interval the records are recorded in. Setting a very high value for ValidDuration can lead to situations where a user who removes all his data is still accounted for unless a record of zero usage is created.

Pros:

- Can be used to detect difference between zero usage and missing records
- No state required on storage system/sensor (different from time duration where you need to know time since previous record)
- Clear handling of overlapping records for record aggregation model

Cons:

- More than one UR is needed to account for usage
- Hard to define "good" value for ValidDuration
- Makes assumption that record information is valid for all the ValidDuration period (or until new record is created)

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