Maximum tolerable period of disruption (MTPOD) is the maximum amount of time that an enterprise's key products or services can be unavailable or undeliverable after an event that causes disruption to operations, before its stakeholders perceive unacceptable consequences.
Maximum tolerable period of disruption Wikipedia
The BSI Group standard BS 25999 requires the dependencies of critical activities to be identified (other activities, assets, resources, suppliers and outsource partners).
BS 25999-2, 20 Nov. 2007 Section 4 says that the goal of a Business Impact Analysis BIA is to "determine the impact of any disruption of the activities that support the organization's key products and services."
A key aspect of determining the impact of a disruption is identifying what BS 25999 calls the "maximum tolerable period of disruption" (MTPOD). BS 25999 defines MTPOD as the "duration after which an organization's viability will be irrevocably threatened if product and service delivery cannot be resumed." MTPOD is just a useful metric that determines how much unavailability an organization can stand before everything crashes and burns and can't be put back together again.
The MTPOD is also known as "maximum acceptable outage" and "maximum allowable outage", in both cases the corresponding acronym is MAO.