Technical description of the product or service. Performance of the goods or services at the event. Technical and Performance specifications can be very detailed. To save any misunderstanding it is best that the specifications contain all three types of description. The specification should be written as clearly and concisely as possible.
Diagrams are an excellent communication medium.
The floor plan or site map is probably the most important. Too much detail can be a risk in that the supplier may miss the important aspects of the event in the smog of data. In a multiple bid for the contract, the event manager will need to evaluate all the tenders. There are a number of formal processes to this that are used in project management. Perhaps the most common is to create an evaluation grid or matrix.