Final answer:
The space about the altar designed for the clergy and choir in a church is known as the choir, and the bema in Eastern Orthodox and Byzantine architecture, often separated from the nave by a templon or iconostasis.
Step-by-step explanation:
The space about the altar of a church for the clergy and choir, often elevated above the nave and separated from it by a railing or screen, is known as the choir. The bema is a specific term for where the clergy stand around the altar, particularly in Eastern Orthodox and Byzantine church architecture. This area is often demarcated by a templon, which in later Byzantine architecture evolved into what is known as an iconostasis, a wall of icons and religious paintings. The choir not only accommodates the clergy and sometimes the choir but also plays a critical role in the liturgical functions of the church, framing the sacred ceremonies that take place at the altar.