Throughout this document, the words that are used to define the significance of particular requirements are capitalized. These words are:
This word or the adjective "REQUIRED" means that the item is an absolute requirement of this specification.
This phrase means that the item is an absolute prohibition of this specification.
This word or the adjective "RECOMMENDED" means that there may exist valid reasons in particular circumstances to ignore this item, but the full implications should be understood and the case carefully weighed before choosing a different course.
This phrase means that there may exist valid reasons in particular circumstances when the listed behavior is acceptable or even useful, but the full implications should be understood and the case carefully weighed before implementing any behavior described with this label.
This word or the adjective "OPTIONAL" means that this item is truly optional. One vendor may choose to include the item because a particular marketplace requires it or because it enhances the product, for example; another vendor may omit the same item.