The bid specification may ask you to give contact information about existing and previous clients who have engaged you on comparable work and who can be approached to vouch for the quality and efficiency of your services. This is a sensible requirement, since it allows prospective new clients to discover what you are like to work with and how competently you have gone about similar assignments. You may be required also to supply site addresses where the client can view your work or see evidence of its implementation.
It is essential to respond accurately and conscientiously to this requirement: after all, if you don't have the experience or the confidence to name other clients who can provide references, what are you doing bidding for this contract? A key item of information is the identity and address of the client manager or unit responsible for employing your services. Do not make the mistake of phrasing the response in terms that are incomplete or vague, as if to impede the possibility of one client talking to another.