(patentlaw) To include, contain, or be made up of, defining the minimum elements, whether essential or inessential, to define an invention. ("Open-ended", doesn't limit to the items listed; cf. compose, which is "closed" and limits to the items listed.)
Usage notes
Traditionally, a team comprised its members, whereas the members composed the team. (The Associated Press Stylebook advises journalists to maintain this distinction.) The sense "compose, constitute"—as in "the members comprise the team"—is sometimes considered incorrect. According to Webster's Dictionary, it dates back to the late 18th century, when it was usually found in technical writing, but Webster's indicates that it is becoming increasingly common in nontechnical literature as well. The American Heritage Dictionary and Random House Dictionary also state that it is an increasingly frequent and accepted usage.
In the passive voice, the use of "of" with comprise (i.e. "is/are comprised of") may be regarded as tautological because the same meaning can be expressed in the active ("comprises") without an "of", or with "composed of", which is both synonymous and non-tautological (since "compose" in this sense always requires an "of").
In most varieties of English, the use of "of" with the verb in the active (rather than passive) tense is consistently treated as incorrect, hence *"the UK comprises of four countries" and *"four countries comprise of the UK" are proscribed. Some Asian dialects are exceptions, including Malaysian English (quite commonly), and to varying degrees Indian, Singaporean, and others.
In patent law, the term "comprising" is "open ended" in most jurisdictions, but may be presumed to be a "closed" listing in other jurisdictions.