What can be defined as the maximum acceptable length of time that elapses before the...

One of the results of a Business Impact Analysis is a determination of each business function's Recovery Time Objectives (RTO). The RTO is the amount of time allowed for the recovery of a business function. If the RTO is exceeded, then severe damage to the organization would result.

The Recovery Point Objectives (RPO) is the point in time in which data must be restored in order to resume processing.

Reference(s) used for this question:

BARNES, James C. & ROTHSTEIN, Philip J., A Guide to Business Continuity Planning, John Wiley & Sons, 2001 (page 68).

and

And: SWANSON, Marianne, & al., National Institute of Standards and Technology (NIST), NIST Special Publication 800-34, Contingency Planning Guide for Information Technology Systems, December 2001 (page 47).