The second and third arguments are optional, and they specify the form of the matrix. The other columns of A are assumed to be zero. There are also two off-diagonal elements in each triangle of P that are constrained to be equal, and they have an initial value of 0.2. You can also describe the model by a set of linear equations combined with variance and covariance specifications, using notation similar to that originally developed by P. Bentler for his EQS program. The displayed output can be in either equation form or matrix form.
Commas separate the equations.
The coefficients to be estimated are indicated by names. If no name is used, the coefficient is constant, either equal to a specified number or, if no number is used, equal to 1. The STD and COV statements define the diagonal and off-diagonal elements in the matrix. The parameter specifications in the STD and COV statements are separated by commas. Identical coefficient names indicate parameters constrained to be equal.