ABSTRACT
A time interval can be defined by only two dates (and times), i.e. by values from-to, in the simplest case. For investigational repeating tests are usually needed to limit their availability not only for a fixed period, but also on the periodic time, e.g. weekly or fortnightly intervals (for school exercises). However, any other repetition period is not excluded. Also need to be able to exclude from the defined time and certain periods, e.g. holidays, vacation, and other longterm forward unplanned outages. Certain periods, e.g. holidays, vacation, and other long-term forward unplanned outages also need to be able to exclude from the defined time.
