The request for proposal (RFP) approach has been used by the information technology (IT) industry for several years. This approach allows the purchaser to focus on actual functional requirements rather than being confused with the various technologies supplied by vendors. Time is well spent defining mandatory requirements and this approach gives a clearer understanding of how the technology will achieve our goals. Once mandatory requirements and "nice to have" features are defined, we can send out an RFP to allow vendors using different technologies to present proposals on how they will meet our requirements as well as expounding on their ability to provide further enhancements.
The rapid evolution of control products was, and still is, many times faster than the construction timeline for most large projects. Specifying automation products in the original design ensures obsolescence and feature-limited products.