Basic question about tilesets

For the first time, I've been doing some minor editing of tilesets, and I gradually realized there was a really important tile I couldn't find: the 'center' water tile, without any bordering land. This tile:



Because the RTP only has this:


The manual says something about a "Group Pattern (refers to group of tiles with one in the center and 1 in each of the 8 directions)" when there are clearly only four tiles.

Am I missing something obvious here?

This article explains the construction of autotiles. While written for Ace, it applies to MV as well. You just need to mentally change the number 32 to 48 and 16 to 24 for it to work for MV.

http://blog.rpgmakerweb.com/tutorials/anatomy-of-an-autotile/

yes, because the autotiles are not four (or five) tiles, they are sixteen (or twenty) quarter tiles.
The tutorial linked above explains it in more detail, but the center piece you're looking for is inside the autotile - just overlapping instead of exclusive like you assumed.

Alright, thanks. Feels a little strange to me, but it makes sense.