OP 1 Optimization process has not converged.
OP 2 Unsuccessful optimization: a parameter has gone out of bounds.
OP 3 Unsuccessful optimization: the function appears to be constant.
OP 4 Unsuccessful optimization: no progress can be made.
OP 5 Standard errors are not available, because information matrix is singular.
OP 6 The calculated likelihood may be wrong because of missing fitted values.
OP 7 Fitted curve is close to, or has reached limiting form.
OP 9 No scalar was specified for value of general function (use MODEL [FUNC]).
OP 10 Fitted values or general function value not changed by model calculations.
OP 11 There are not enough non-missing data to fit the model.
OP 12 Invalid model formula for FITNONLINEAR (only variates and 1 factor allowed.
OP 13 Invalid model formula for FITCURVE (only 1 variate and 1 factor allowed).
OP 14 Invalid error distribution.
OP 15 Invalid attempt to reverse sense of curve.
OP 16 Invalid attempt to constrain origin: constraint is ignored.
OP 17 Invalid attempt to omit constant: constant is retained.
OP 18 The constant must be omitted with Poisson likelihood.
OP 19 The asymptote has been reversed.
OP 20 No parameters have been specified (use directive RCYCLE).
OP 21 The fitted curve has a vertical asymptote within the data range.
OP 22 A parameter has been included twice.
OP 23 A text structure in a function does not match any current parameter label.
OP 24 Information is not available to estimate variance of function.
OP 25 No model calculations have been specified (use option CALCULATION).
OP 26 The initial value of a parameter is out of range.
OP 27 S.e.s of linear parameters are not available when terms are smoothed.
OP 28 Nonlinear models cannot be fitted with a matrix of weights.
OP 29 RFUNCTION cannot be used for curves with separate nonlinear parameters.
OP 30 Invalid initial optimization values.
OP 31 Missing value returned in general function optimization.
OP 32 Curve fitting may not have converged fully.