And that's exactly what it is: a RF Power Combiner simply combines (sum) different signals in a single output. In the above case, the signals are transmitted over port B and C go out through that output (A).
The body mass index (BMI) or Quetelet index is a value derived from the mass (weight) and height of an individual. The BMI is defined as the body mass divided by the square of the body height, and is universally expressed in units of kg/m 2, resulting from mass in kilograms and height in metres.
Abbreviated BMI. BMI is a person's weight in kilograms (kg) divided by his or her height in meters squared.