4.4 Joint preparation of the SRS
The software development process should begin with supplier and customer agreement on what the
completed software must do. This agreement, in the form of an SRS, should be jointly prepared. This is
important because usually neither the customer nor the supplier is qualiÞed to write a good SRS alone.
a) Customers usually do not understand the software design and development process well enough to
write a usable SRS.
b) Suppliers usually do not understand the customerÕs problem and Þeld of endeavor well enough to
specify requirements for a satisfactory system.
Therefore, the customer and the supplier should work together to produce a well-written and completely
understood SRS.
A special situation exists when a system and its software are both being deÞned concurrently. Then the functionality,
interfaces, performance, and other attributes and constraints of the software are not predeÞned, but
rather are jointly deÞned and subject to negotiation and change. This makes it more difÞcult, but no less
important, to meet the characteristics stated in 4.3. In particular, an SRS that does not comply with the
requirements of its parent system speciÞcation is incorrect