The Siddur we use for Yom Tov is known as a Machzor. What does it mean and where did this originate?
Some siddurs have the phrase "Ki Kel Melech Chanun V'Rachum Ata" at the conclusion of Ya'aleh v'Yavo. Some have Melech in parentheses; some don't have it at all. Can anyone tell me something about ...