=== Feature sets ===
There are many cases where we want to display different level of detail regarding support for features. So it is somewhat helpful to organize feature features into feature sets.
'''EXAMPLES:''' ''Each various values of a given CSS property are considered individuals features where the property as a whole is considered a feature set (see [https://developer.mozilla.org/en-US/docs/Web/CSS/display display]). Each attribute and methods are considered individuals features of a given API, which is a feature set. Even a methods can be a feature set if it has different signature, and each of them is an individual feature (see [https://developer.mozilla.org/en-US/docs/Web/API/MozMobileMessageManager.getSegmentInfoForText getSegmentInfoForText]).''