Changes to Version 0.7-0

   o Fixed problem with analytic gradient, which caused convergence problems for some models.

   o Simplified optimization.

   o Added modification indices (preliminary version).
    
   o Some changes to start values.
    
   o Added RMSEA to fit indices. 
   
   o Added Klein dataset. 
   
Changes to Version 0.7-1

   o Replaced F with FALSE as logical, F with f as variable.
   
Changes to Version 0.7-2

   o Fixed tsls examples to run even if a global variable named F exists.
   
Changes to Version 0.7-3

   o Fixed bug in start-values routine that affected unstandardized models.
   
   o Added code to try to detect under-identified models.

Changes to Version 0.7-5

   o Made arguments to method functions consistent with generics (mostly adding ...).
   
Changes to Version 0.7-6

   o Check for negative degrees of freedom.
   
Changes to Version 0.7-7

   o Fixed bug in sem.default and startvalues that prevented the model from being fit when there are all equality constraints affect precisely the same numbers of parameters.
   
   o Fixed bug in tsls.formula that could cause the wrong variable to be identified as the response (causing the fit to fail).
   
   o Added code to detect more instances of nonconvergence.
   
   o Other small changes to code and documentation.
   
Changes to Version 0.7-8

   o Fixed bug in tsls.formula that could prevent model formula from being evaluated (producing an error).
   
Changes to Version 0.7-9

   o Fixed bug that caused a model with only one endogenous variable to fail.
   
   o Improved computation of RMSEA confidence limits
   
Changes to Version 0.8-0

   o Put in a warning for (unfixed) observed or latent variable without either variance or error-variance term specified (i.e., double-headed arrow). As far as I know, this will always produce an error.

Changes to Version 0.8-1

   o Fixed a bug in tsls.formula that caused the function to fail when the printed representation of the instruments formula extended over more than one line.
   
Changes to Version 0.8-2

   o Fixed a bug in startvalues() and sem.default() that caused the variables (observed + unobserved) in the model to be counted incorrectly in some (unusual) circumstances.
   
Changes to Version 0.9-0

   o Added function specify.model() to simplify the process of sem model specification.
   
   o Added boot.sem() to compute bootstrapped standard-error estimates and confidence intervals for sem parameters.
   
   o sem package now has a namespace.
   
   o Added digits argument to path.diagram(), as suggested by William Revelle.
   
   o New argument raw to sem() to accommodate raw moment matrices (for models with intercepts, after a suggestion by Mike Stoolmiller). Added generic function raw.moments() with formula and default methods to compute raw-moment matrices.
   
   o Small changes.
   
   
