number-of-elements:
the number of elements in the Sequence
Examples:
John was the first of five patients that the doctor saw
first-element: John
number-of-elements: five
he played the trumps in sequence
Comment:
It is not necessary to specify a number-of-elements or to list the
element of an ensemble. If you do, the system will try
to maintain consistency by requiring that the number of element
is at least as large as the specified number-of-elements