Update pagination descriptions

Some of the recommendations in the previous pagination specification
were too hard to implement in practice. These changes mirror some of
the internal pagination guidance changes made in AWS over the years.

docs/source/1.0/spec/core/behavior-traits.rst

@@ -381,23 +381,17 @@ Pagination Behavior
 
 #. Only one list or map per operation can be paginated.
 
-#. Paginated responses MUST NOT return the same item of a paginated result
-   set more than once (i.e., a paginated result set is a disjoint union of the
-   subsets partitioned by the referenced ``pageSize`` input member and the SLA
-   defined by the service).
+#. Paginated responses SHOULD NOT return the same item of a paginated result
+   set more than once.
 
-#. If a paginated request returns data in a sorted order that is not an
-   immutable strict total ordering of items, then the paginated request MUST
-   provide a temporally static view of the underlying data that does not
-   modify the order topology during pagination. For example, a game’s
-   leaderboard of top-scoring players cannot have players move from position
-   #10 to position #12 during pagination, the last player on page N has to
-   have a higher score than the first player on page N+1, no players that
-   exist when pagination begins are to be skipped, and players MUST NOT be
-   repeated due to moves in the underlying data.
+#. Services SHOULD NOT return items in a paginated result set that have been
+   deleted during the pagination process, but before reaching the relevant
+   page.
 
-#. If pagination is ordered and newly created resources are returned, then
-   newly created resources MUST appear in order on the appropriate page.
+#. Services MAY include newly created items in a paginated result set on a
+   not yet seen page. If pagination is ordered and newly created items are
+   returned, then newly created items MUST appear in order on the appropriate
+   page.
 
 
 Client behavior
@@ -407,7 +401,9 @@ Smithy clients SHOULD provide abstractions that can be used to automatically
 iterate over paginated responses. The following steps describe the process a
 client MUST follow when iterating over paginated API calls:
 
-#. Send the initial request to a paginated operation.
+#. Send the initial request to a paginated operation. This request MAY
+   include input parameters that are used to influence the starting point
+   at which pagination occurs.
 
 #. If the received response does not contain a continuation token in the
    referenced ``outputToken`` member, then there are no more results to