What's the point of the top-middle autotile tile?

[Twin Matrix]

I read up on XP's site that it's the "parent pattern", and that when two autotiles share the same parent pattern, they go seamlessly next to eachother or something. But I don't get this.

I was mixing with autotiles the other day, and I accidentally had done something which caused the autotile to lose its border when next to other autotiles. OK, so that sounds a little confusing. Allow me to explain briefly. :3

You have autotile A, dirt. And autotile B, water. Normally when these two are next to eachother, you'd see some grass between them. But I messed something up which caused the little grass to disappear, and the dirt and water tiles next to eachother were like the 'full' tile. I hope you understand. Does this have something to do with parent patterns? I deleted them because it was messed up, but I'm wondering.

Thanks!

 

[Sarkilas]

I think it does nothing. At first I thought it showed up behind transparent bits of the autotile, but the only reason Enterbrain apparently put it there was so you could see which autotile was for which tileset. For instance, the walls have the specific wall tile so you can link it to the specific tileset. Kind of ridiculous :P

 

[Cryranos]

It's like the different water tiles, they seamlessly go together when placed next to each other.

The different grass and sand autotiles do this.

 

[Nickster]

It's like the different water tiles, they seamlessly go together when placed next to each other.

The different grass and sand autotiles do this.

except custom ones dont seem to work.

 

[Rey_JJJ]

Hm, is this just a sort of basic autotile question?
Do you know exactly how the "Parent Tile" works?
I'll elaborate if you don't.