Time and Time Again: the Origins of Asserted Versioning:
Versioning is a widely used technique within the IT community. It is used to keep track of a chronological series of changes to objects of interest – in our example, insurance policies. In its simplest form, a non-temporal table is converted into a version table by adding a versioning date or timestamp to the primary key of that table. It is usually added as the low-order part of the primary key, in order to keep all versions for the same object together. In the version table, all rows with primary keys that are identical except for the versioning date or timestamp are rows that represent what was the current state of the object beginning on the versioning date and, usually, continuing until a newer version is added to the table.