Most layouts will supply multiple page masters, each of which is used in a different situation. Most commonly this is used for even- and odd-page layouts for double-sided printing.
This function returns a
repeatable-page-master-alternatives node that is
added as a child of the
page-sequence-master node available as the
FlowTree instance. Its calling
masterName argument is a string you
use to give a name to this set of alternatives. That
name will passed to the
pageSequence() function to
designate that this set of alternatives is to be used
with that page sequence.
The remaining positional arguments will be the nodes
conditionalMaster calls, one for each
alternative page layout in this master set.