What is mol rxn? Units in thermochemistry calculations.

What is the thermochemistry unit “mol-rxn”? The “mol-rxn” unit is especially confusing because in most reactions, the stoichiometry of each reactant and product differs. There is simply no such thing as a reaction mole unless we refer to a mole of reactions, i.e., 6.022E23 reactions occurring in concert, which we are certainly not.