Creation and implementation of designated time points in a version expiration environment

A non-transitory storage medium having stored therein computer-executable instructions which, when executed by one or more hardware processors, implement and/or cause the performance of operations comprising:

• receiving a most recent backup version of client data;
• marking the most recent backup version to indicate that the most recent backup version has no expiration time;
• determining a currency span of an earlier backup version that is the backup version whose creation time is next most recent after a creation time of the most recent backup version;
• identifying all curtains in the currency span, each of the curtains being associated with a respective rule concerning a life of the earlier backup version;
• applying each of the rules to the earlier backup version, and whichever rule whose application results in the latest expiration time for the earlier backup version is the controlling rule;
• and
• assigning an expiration time to the earlier backup version according to the controlling rule.