what layer am I on?

[Thorin]

I'm planning on collecting some gold (say, 30 stacks?), so I started looking for the ideal layer for gold ore.  That led me to the Altitude page on the wiki, where I quickly learned there's multiple definitions being bandied about, all referred to as "layer".

Turns out that "layer" means where the bottom of a block would be, while the Y value shown in F3 is where your feet are plus 1.6 to get to the height of your eyes.  So if your Y value in F3 is 64.6, then your feet are standing at exactly layer 63, and the block you're standing on is actually a block on layer 62.

When mining for gold, apparently layer 28 is the perfect layer based on how much ore and how little lava and gravel there is.  Which means my feet should be on layer 28, so my F3 value should be 29.6.

Now I wonder how this all works with Zombe's Mod Pack and Rei's Minimap, which both show my Y value but are 1 apart (one will show 28, the other will show 29).

[Thorin]

A sample of the confusion:

The sea level is at 63, not 62 as the article states. Evidence: If you stand on a block at sea level (shore) like in the example in the article, F3 will show that your eyes are at ≈Y64.6. Eye height is 1.6 blocks above feet (also stated in article), and 64.6 - 1.6 = 63, not 62. Also, in the code it sets "average terrain height" to 63 in normal worlds (as opposed to superflat, which has average height 4 in the code), and experimenting with this value moves the sea level.

- Indeed, sea level is 63, but highest sea layer is 62. (Some layer X is between altitudes X and X+1). I admit the article is ambiguous, so I'll correct it.

[Mr. Analog]

... or strip mining