BRIN indexes

Reposting because I received no reply from a previous inquiry as "9.5 new
features".

With regard to BRIN indexes:

http://www.postgresql.org/docs/9.5/interactive/brin-intro.html

62.1. Introduction
....
"A block range is a group of pages that are physically adjacent in the
table; for each block range, some summary info is stored by the index."

From the above, may I presume that it is best to cluster (or sort), the
table based on the intended
BRIN column(s) before actually creating the index to insure the pages are
adjacent? If so, should
that not be included in the documentation, instead of implied?

--
*Melvin Davidson*
I reserve the right to fantasize. Whether or not you
wish to share my fantasy is entirely up to you.