There is always more than one way to realize a key system function. Candidate solutions should take into consideration previously developed hardware and software components, non-developmental items, and COTS hardware and software.

In order to limit the scope of the trade study, the list of candidate solutions should be limited to those that are feasible (cost, schedule), and low risk. Eliminate candidates that don't satisfy the associated system requirements for the key system function. Keep the list of candidates as small as possible.