The model can be specified using an algebraic format where the plus sign (+) is used to add together components, and parentheses specify which subgroups a multiplicative component modifies. The algebraic format is translated by XSPEC into the correct format based on component order (see below). Whenever the model parameter list is written out, an algebraic description of the model is included. Note, however, that the correct use of addcomp and delcomp does require knowledge of the component order.