The Project Management Body of Knowledge 5th Edition (PMBOK) states in the glossary
Quality Requirement- a condition or capability that will be used to assess conformance by validating the acceptability of an attribute for the quality of a result.
I understand the individual words, however when combined in this way I find myself lost. Can this be put simply?
I understand that as:
"This attribute needs to meet all defined standards of quality. To verify that it does, check this condition / that it has this capability."
Specifically, the requirement would be either: '[attribute] passes [condition]' or '[attribute] successfully implements [capability]'.
The quality of the product (result) is only as good as the sum of its parts (attributes). A condition or capability is the predefined specification. Conformance of the attribute is how well this attribute meets the predefined specification. The quality of the result is the overall product assessment based on all the attributes of the product meeting, or conforming, to their predefined specs/quality requirement.
Requirement- a condition or capability that will be used to assess conformance by validating the acceptability of an attribute
Take quality out of it to start - a requirement is something you measure (condition or capability) to determine if the product is acceptable (conforms).
A quality requirement is a requirement that is measured on quality
Compare that with a cost requirement - which is a requirement measured on cost. Or a security requirement, or any other type of requirement. They're all things you measure to determine if what was delivered is acceptable for what was promised.
Does that help?
