i. The heat produced by combustion of unit quantity of a solid or liquid fuel when burned at constant volume in an oxygen bomb calorimeter under specified conditions, with the resulting water condensed to a liquid.
Ref: ASTM
ii. The amount of heat liberated by the complete combustion of unit weight of coal under specified conditions; the water vapor produced during combustion is assumed to be completely condensed.
Ref: BS, 4
iii. At constant pressure, the number of heat units that would be liberated if unit quantity of coal or coke was burned in oxygen at constant pressure in such a way that the heat release was equal to the sum of the gross calorific value at constant volume and the heat equivalent of the work that would have been done by the atmosphere under isothermal conditions had the pressure remained constant.
Ref: BS, 1
iv. At constant volume, the number of heat units measured as being liberated per unit quantity of coal or coke burned in oxygen saturated with water vapor in a bomb under standard conditions, the residual materials in the bomb being taken (suitable corrections having been made) as gaseous oxygen, carbon dioxide, sulfur dioxide, nitrogen, liquid water in equilibrium with its vapor and saturated with carbon dioxide, and ash.