Changes in gnm 0.7-2
=======================

Improvements
------------

    o	Extended use of the 'eliminate' argument of gnm() to allow crossed 
	factors - this also fixes bug which occurred when interactions were 
	eliminated in the presence of lower order terms involving other factors 

Changes in Behaviour
--------------------

    o	'vcov' returned by gnm() now has no rank attribute (as before, the
	rank is returned as the separate component 'rank').

Bug Fixes
---------

    o	Changed the calculation of 'df.residual' returned by gnm() to 
	correctly take account of zero-weighted observations (as in glm()).

    o	When gnm() is called with arguments x = TRUE or VCOV = TRUE, the 
	returned matrices now include columns of zeros for constrained 
	parameters.

    o	Corrected evaluation of model frame in gnm() so that if data is missing, 
	variables are taken from environment(formula), as documented. Modified 
	evaluation of plug-in functions to be consistent with this, i.e. 
	objects are taken from environment(formula) if not in model frame.

    o	MPinv() now checks that the diagonal elements of an `eliminate'd 
	submatrix are all non-zero and reports an error otherwise.



Changes in gnm 0.7-1
=======================

New Features
------------

    o	Topo() introduced for creating topological interaction factors.

    o	anova() implemented for objects of class c("gnm", "glm").


Improvements
------------

    o	Diagnostic messages given by gnm() have been improved.

    o	Step-halving introduced in main iterations of gnm() to ensure deviance 
	is reduced at every iteration.

    o	getContrasts() now (additionally) reports quasi standard errors, when
	available.

    o	Calls to gnm() plug-in functions are now evaluated in the environment 
	of the model frame and the enclosing environment of the parent frame 
	of the call to gnm(). This means that variables can be found in a 
	more standard fashion.


Changes in Behaviour
--------------------

    o	The 'data' argument of Nonlin() is defunct: Nonlin() now identifies 
	variables to be added to the model frame as those passed to unspecified
	arguments of the plug-in function or those identified by a companion 
	function to the plug-in, which is of a specified format.

    o	The (optional) 'start' object returned by a plug-in function can no 
	longer be a function, only a vector. However it may now include NA 
	values, to indicate parameters which may be treated as linear for the 
	purpose of finding starting values, given the non-NA values.


Bug Fixes
---------

    o	The 'eliminate' argument of gnm() now handles functions of variables in 
	the given formula e.g. ~ strata(A, B), ~ as.factor(A):as.factor(B), etc. 

    o	gnm() was giving an error for models with either no linear parameters, 
	or none specified by the 'start' argument, this is now fixed.

    o	Long calls to plug-in functions caused problems in parsing the model 
	formula: now fixed.

    o	gnm() now only restarts after failing if there are unspecified nonlinear
	parameters.

    o	gnm() now returns NULL if model fails.

    o	Bug fixed in calculation of starting values for gnm() that occurred when some
	parameters were constrained.
	
