These components may be either additive, multiplicative, mixing, or convolution.
Multiplicative components multiply the model by an energy-dependent factor.
Mixing components link models for different datagroups. Convolution models modify the current model. Multiplicative, mixing, and convolution components can act on individual components, on groups of components, or on the entire model. The model command defines the model to be used and prompts for the starting values of its parameters. The user also can set the allowed range of the parameter.