According to Robert's Rules of Order Newly Revised (RONR), this motion is applicable when each of the different parts, although relating to a single subject, is capable of standing as a complete proposition without the others.
[2] The motion is made by saying, for instance, "I move to divide the resolution so as to consider separately...."[3] A motion to divide the question is not required when a single motion seeks approval of a series of propositions or resolutions on different subjects.
Any member may obtain separate discussion and voting on any of the unrelated propositions or resolutions by making a demand for separate consideration, at any time before the unified motion is put to a vote.
[4] In the British House of Commons, a formal motion is not required to divide the question; since 1888, the Speaker has held that a question consisting of two or more propositions, each of which is able to stand on its own, can be divided on the objection of any Member of Parliament.
[5] In the European Parliament, the division of a question is known as split voting and may be requested by a political group or at least 40 members, when "the text to be put to the vote contains two or more provisions or references to two or more points[...]".