Explanation:
The contract should specify the number of subscribers permitted to use the site at any one time. Physical security measures are not a part of the contract, although they are an important consideration when choosing a third-party site. The total number of subscribers is not a consideration; what is important is whether the agreement limits the number of subscribers in a building or in a specific area. The references that other users can provide is a consideration taken before signing the contract; it is by no means part of the contractual provisions.