Each RFP defines its own set of rules and guidelines, and comes with its own timeline. Important criteria are the maximum amount that is available per project, and the timeline during which the RFP is open for submissions.
In the detailed description of the RFP, you will find other conditions, often specified as ‘Must haves’ ‘Should haves’ and ‘Could Haves’. Also non-functional requirements may be defined, such as conditions on performance, documentation, security, etc.
Be sure to read all conditions in the RFP carefully, especially if you are submitting a proposal to multiple RFPs.