Tile Checking

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As I'm trying to fix the shovel on Zenkou, which I'm almost done fixing for the known bugs, I need to know how to check if one tile is in the same level as another.

I know it sounds wierd but let me explain.
If you're digging for a shell (diggable in sand only) and you're in the middle of the jungle and dig on sand, you can still get a shell. That's kind of improbable in real terms. So what I'm trying to do is find out how to check in the sand tile is in the same level as a deepwater tile.

All I really need to know is how to check the tile in a script.
For example, these 2 tiles are grass tiles on Zenkou.

PHP Code:

0x31,0x1A4 


So I see that a tile can be either a "number x(by) number" or "number x(by) letters/numbers".
This is confusing to me because I've never worked with tiles I didn't already have in a script.

What I'm asking for is help with figuring out what a certain tile is.