A list containing three data.frames and three formula, one for each.xdata.frame containing the variables on the right-hand side
of the model formula.ydata.frame containing the variables on the left-hand side
of the model formula.gdata.frame containing the variables, if any, after
the conditioning bar | of the model formula.x.formulaformula containing the right-hand side
of the model formula.y.formulaformula containing the left-hand side
of the model formula.g.formulaformula containing the formula after the
conditioning bar | of the model formula.