You're required to write either RANGE or ROWS to start a frame clause,
but the documentation incorrectly implied this is optional. Noted by
David Johnston.
The frame_clause> can be one of
-[ RANGE | ROWS ] frame_start>
-[ RANGE | ROWS ] BETWEEN frame_start> AND frame_end>
+{ RANGE | ROWS } frame_start>
+{ RANGE | ROWS } BETWEEN frame_start> AND frame_end>
where frame_start> and frame_end> can be
and the optional frame_clause
can be one of
-[ RANGE | ROWS ] frame_start>
-[ RANGE | ROWS ] BETWEEN frame_start> AND frame_end>
+{ RANGE | ROWS } frame_start>
+{ RANGE | ROWS } BETWEEN frame_start> AND frame_end>
where frame_start> and frame_end> can be
one of