This is a measure of the extent to which the software must perform its intended function over a period of time. If the effect of a software failure is only a slight inconvenience then RELY is set very low. If a failure would risk human life then RELY is set very high.

Rating Levels	Description	EM
Very Low	Slight inconvenience	0.82
Low	Low, easily recoverable losses	0.92
Nominal	Moderate, easily recoverable losses	1.00
High	High financial loss	1.10
Very High	Risk to human life	1.26
Extra High		n/a

This cost driver can be influenced by the requirement to develop software for reusability. See the description for RUSE.