classes(): A named vector with the classes of the data
contained in the pim.environment
names(): For an object of class pim.environment the names
of the variables in the object. For an object of class pim.poset,
the name of the poset functions inside the environment
compare(): A character value indicating how the comparison
is defined in a pim.poset object, or the poset-slot of
a pim.environment object respectively.
model(): a character value that displays
the type of model (difference, marginal, regular or customized)
link(): a character value that displays
the type of link (difference, marginal, regular or customized)