WorkSafe Victoria describes the safe working load as the maximum weight of unit loads that should be placed on racking for it to remain safe, available from the manufacturer’s instructions, and says changes to the racking configuration alter it.
A figure printed on a website would belong to no rack you own. So every plate on this site carries the only instruction that is true of all of them: see the manufacturer’s rating. The racking bay explains what a real sign shows and who may change it.