I'm not sure what you are asking, but, if you are looking for a definition and how they work, look below..
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Answer:
A government within which a monarch agrees to share power with a parliament and abide by a constitution; conjointly referred to as a constitutional autocracy. Most constitutional monarchies use a parliamentary system within which the Monarch could have strictly Ceremonial duties or may have Reserve Powers, looking on the constitution. they need a directly or indirectly elective prime minister United Nations agency is that the head of state and exercises effective political power.