In this paper, an interactive computer program for estimating the parameters of spatial choice models with multiattribute utilities is presented. The models to be calibrated may be unconstrained, singly constrained, or doubly constrained random utility choice or entropy-maximizing interaction models. Utilities may be associated with choice alternatives (zones) or with the choices themselves (trips). The program maximizes the likelihood of the choice matrix (trip table) given observed choices (trips) using a combination of gradient search and Newton-Raphson iteration methods. 

The paper contains a specification of the range of models that can be calibrated with the program and a description of its solution algorithm and organization, as well as an illustrative application and a listing of the source code.