Most companies have their own flavour of a product requirements document. The name of the document and the templates tend to vary from company to company.
Even though each format captures business and customer requirements slightly differently, essentially the document should provide the reader (business analysts, solution architects and developers) the pieces (the market needs, the business rules, the customer benefits, pricing information) that make up the product.
More importantly, the document has to be suited to the company and its needs. There is no value writing a requirements document that will not provide the reader the information to perform the next function in the product development process.
Furthermore, the requirements document should always avoid presenting a solution as it limits the way in which the product is finally constructed.
Check out what Scott from Tyner Blain has to say on the subject of product requirements.