An object of class "anylist" is
  a list of objects that the user intends to treat in a similar fashion.
For example it may be desired to plot each of the objects
  side-by-side: this can be done using the function
  plot.anylist.
  
The objects can belong to any class;
  they may or may not all belong to the same class.
In the spatstat package, various functions produce
  an object of class "anylist".