The definition of symbiosis has varied among scientists. Some believe symbiosis should only refer to persistent mutualisms, while others believe it should apply to any type of persistent biological interaction (i.e. mutualistic, commensalistic, or parasitic).
The Golden Pledge, which is a System Plus Warranty with a 20 year leak guarantee, can pay for itself within the first ten years, sometimes many times over. The System Plus transforms the normal warranty by removing the small print.
In Australia, negative pledge lending took off after a substantial deal by Pioneer Concrete in 1978. It was a new way of lending, which allowed the banks to lend to corporations, something previously the domain of life insurers. Negative pledge clauses are almost universal in modern unsecured commercial loan documents. The purpose is to ensure that a borrower, having taken out an unsecured loan, cannot subsequently take out another loan with a different lender, securing the subsequent loan on the specified assets.