c1 is a quantity of café au lait/latte/café con leche/cappuccino/flat white/coffee with heated dairy [or similar] product/creamer/whitener la1=g1, addition warm by standard g2.
mekso operator: continued fraction, Kettenbruch notation; for ordered input (X1, X, where: X1 is an ordered pair of functions and X2 is a free or dummy variable/input/index which ranges through set X3 in order(ing) X4, the result is K(X for Kettenbruch notation K.
x1=c1 is made of/contains/is a quantity of espresso [coffee beverage] from beans x2=c2 with crema x3
(the foam with a creamy texture that forms as a result of the pressure).