Methods for class "units".
# S3 method for units
print(x, ...)
  # S3 method for units
summary(object, ...)
  # S3 method for units
rescale(X, s, unitname)
  # S3 method for units
compatible(A,B, ..., coerce=TRUE)Objects of class "units" representing
    units of length.
Conversion factor: the new units are s times the old units.
Other arguments.
    For print.units these arguments are passed to print.default.
    For summary.units they are ignored.
    For compatible.units these arguments
    are other objects of class "units".
Logical. If TRUE, a null unit of length is compatible with
    any non-null unit.
Optional new name for the unit. If present, this overrides the rescaling operation and simply substitutes the new name for the old one.
For print.units the value is NULL.
  For summary.units the value is an object of class
  summary.units (with its own print method).
  For rescale.units the value is another object of class "units".
  For compatible.units the result is logical.
These are methods for the generic functions
  print, summary, rescale
  and compatible
  for the class "units".
An object of class "units" represents a unit of length.
The print method prints a description of the unit of length,
  and the summary method gives a more detailed description.
The rescale method changes the unit of length by rescaling it.
The compatible method tests whether two or more units of length
  are compatible.