In some cases, informal methods offer the convenience of quick testing to see if a model can be validated.In other instances, informal methods are the best available option.In all cases though it is important to note that informal does not mean it is any less of a true testing method.These methods should be performed with the same discipline and structure that one would expect in "formal" methods.
Stier Validation has always been part of the Hazard Analysis and Critical Control Point (HACCP) system, but it is an even greater issue in today’s food safety management systems.
The trust level of the certificate indicates the actions for which you trust the signer.
You can change the trust settings of certificates to allow specific actions.
Even though this has been required since “day 1,” it is surprising how many companies’ HACCP plans contain no validation data.
The ISO 22000 and PAS 220 standards require formal validation of CCPs and operational prerequisite programs (o PRPs).