Example

Let's say that details of a person's absence from their household are captured as evidence.

Each period of absence has a start date and (optionally) an end date. Each period of absence also has a reason for the person's absence, but notably the reason can change during the absence (i.e. the person can be initially absent for one reason, then from a given date continues to be absent but for a different reason).

For a given person, no two periods of absence can overlap (a person cannot be absent in more than one way at any given time). In particular, the person can have at most one open-ended period of absence.

Each separate period of absence is captured as its own succession set of absence; in other words, if the person is absent from the household, and then returns, and then later leaves the household again, the second period of absence is a different succession set of evidence from the first.

Some eligibility/entitlement rules for the person require to derive information from the person's history of absences. Legislation states that a person is eligible for benefit if present in the household, or is absent for the reason of "Education" only.

To simplify these eligibility/entitlement rules, it is desirable to compute a single history of absence details from the person's absence periods (of which there may be zero, one or many). The combineSuccessionSets expression is used to compute this single history of absence details for the person.

Now let's create a history of absences for a Person and work through it as an example.

The person John Smith is absent from his household on these occasions:

• John leaves the household on 1st January 2000 to pursue his college education. Unfortunately, on 28th January 2000, John falls seriously ill and is hospitalized. His absence from the household continues but its reason changes from Education to Medical Treatment. John recuperates and returns home on 8th March 2000.
• John's curtailed college education and subsequent illness leave him with personal problems, and after committing a spate of petty crimes he is jailed on 2nd June 2000. A new absence is recorded for John, with a reason of Incarceration throughout (this particular absence does not vary in reason). He is released from prison on 30th June 2000.
• Determined to make a fresh start, John enlists in the army and is then absent from the household from 10th August 2000 until further notice, with an absence reason of Military.

Three Absence rule objects are populated for John's three periods of absence by the Active Succession Set Rule Object Converter. Each Absence rule object is populated by the succession set of evidence records captured for the related period of absence, e.g. the first Absence rule object is populated with a start date of 1st January 2000 and an end date of 8th March 2000. Each Absence rule object also has a reason attribute with values that vary over time.

A single CombinedAbsence rule object is then created by the combineSuccessionSets expression. The single CombinedAbsence rule object for John has a reason attribute with these values that vary over time:

• prior to 1st January 2000, the absence reason is blank (the default value), as John is not absent at this time;
• from 1st January 2000, the absence reason is Education, John's initial reason for his first absence;
• from 28th January 2000, the absence reason changes to Medical Treatment, in line with the change in reason part-way through John's his first absence;
• from 9th March 2000 (the day after John's last day in hospital), the absence reason changes back to blank, because John is no longer absent;
• from 2nd June 2000, John begins his second period of absence, with a reason of Incarceration;
• from 1st July 2000, the absence reason changes back to blank, because John is no longer absent; and
• from 10th August 2000 until further notice, John begins his third period of absence, with a reason of Military.

The single CombinedAbsence rule object for John also has an exists attribute which simply combines the periods for which the contributing absences each exist.