Represents a layout processing action that should be applied to a user's
layout and contains the ability to apply that specific action. Node changes
that need to be made to the ILF and PLF of a user must not be made until all
changes have been identified and reviewed to see if they are allowed by an
owning fragment and additionally in the case of channels by the channel
definition. After all such actions have been identified and approved then
each implementation of this interface applies its changes in an appropriate
manner based on whether the node is incorporated from a fragment or owned by
the user.
author: mboyd@sungardsct.com