I am happy to report that the ITIL Service Design book contains some good high level guidance on "Requirements Engineering" (Section 5.1). Requirements Engineering is defined as
"the approach by which sufficient rigor is introduced into
the process of understanding and documenting business
and user requirements and ensuring traceability of changes
to each requirement."
ITIL defines three levels of requirements: Functional, Management and Operational and Usability.
The Service Design book is particularly good for those who do not have a background in the Software Development Life Cycle (SDLC). I would highly recommend it to everyone involved in process design, implementation and operational management.