The method defines how the result will be produced; the specification defines what the result means. Both should be versioned, validated, and historically valid objects.
Scope
Method library: A single centralized definition of standard and internal methods; including the source standard number, revision date, and validity status.
Method parameters: Type of instrument to be used, required reagents and standards, operating conditions, calculation formula, unit, decimal accuracy, and reporting rules.
Validation and verification logs: Storing method performance data and verification reports depending on the method.
Specification sets: Different sets of limits based on product, customer, market, or regulation. The same product can be sold to different customers with different specifications.
Warning and action limits: Internal control thresholds defined within the specification limit catch the problem before the specification is exceeded.
Version and validity date: Tracking which specification was valid on which date. A past batch should have been evaluated according to the specification in effect at that time.
Change control: Approval process for method or specification changes, justification, and list of affected products.
A common mistake
The specification is kept in a spreadsheet and manually entered into the system. When the specification is updated, the old limit continues to be used, which can lead to a non-conforming product appearing compliant. The specification should come from a single source, and the evaluation should be automated.