ilities

[Mj_Developer]

Do you know anything about "ilities"? I have found a definition about "ilities". Please help me in understanding it. The resource is at http://en.wikipedia.org/wiki/List_of_system_quality_attributes.

The definition is: Within systems engineering, quality attributes are non-functional requirements used to evaluate the performance of a system. These are sometimes named "ilities" after the suffix many of the words share.

-What does "non-functional requirements" mean?
-What's tense of the "used"?
-What does "after the suffix many of the words share" mean?

[Mister Micawber]

-What does "non-functional requirements" mean?-- They are not physical parts of the system.
-What's tense of the "used"?-- It is non-finite.
-What does "after the suffix many of the words share" mean?-- 'because many of them have the same suffix ('ility')'
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Native English teacher at Mister Micawber's

[Mj_Developer]

Thank you Mister Micawber. What do you mean by "non-finite"?

[Mister Micawber]

Have you used your DICTIONARY?
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Native English teacher at Mister Micawber's

[Mj_Developer]

quality attributes are non-functional requirements used to evaluate the performance of a system

Doesn't "are used" refer to passive voice of present simple?

[Mister Micawber]

No. If you wish to paraphrase:

quality attributes are non-functional requirements [which are] used to evaluate the performance of a system

However, since those words do not exist in the given sentence, 'used' remains the head of a non-finite adjectival clause.
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Native English teacher at Mister Micawber's