What does the term 'shall' denote in API standards?

The term 'shall' in API standards signifies a mandatory requirement that must be adhered to in order to be in compliance with the standard. This terminology establishes a clear expectation that the specified actions or conditions are obligatory. As such, using 'shall' indicates that entities must meet the outlined criteria, ensuring a baseline of safety, quality, or performance that is essential within the industry.

In contrast, the other options imply varying degrees of flexibility or non-mandatory provisions. Recommendations for best practices do not impose forceful compliance, while optional guidelines suggest that adherence is not necessary. An acceptable industry norm may indicate common practices but lacks the binding requirement that 'shall' entails. Thus, 'shall' provides clarity and rigor necessary for standardization in industrial applications.