EOU Gather Mechanics

Length: 96

00: Floor number.
04: Node ID (Irrelevant.)
08: X-coordinate. (Starts from 0, and starts counting from the left.)
0C: Y-coordinate. (Starts from 0, and starts counting from the top.)
14: Node type. (0: Chop, 1: Mine, 2: Take)
18: Gather attempts allowed (Leftovers from EO4.)
1C: Header 1 (Also leftovers from EO4.)
24: Header 2 (Indicates where the gathering tables start.)
28-2B: Tells the game to look at the next table instead if certain conditions are fulfilled. (Only relevant for the 5th Stratum's Chop Points.)
2C: Chance to get the rare item.
30: Chance to get the uncommon item. (Actual chance is NOT EQUAL to the listed chance. Read the Gather Mechanics section for more details.)
34-35: Rare item ID.
36-37: Uncommon item ID.
38-39: Common item ID.
3C: Ambush Chance

The next part is only relevant for the 5th Stratum's Chop points. Ignore this section for all the other gather points. The rooms with the Chop points have the Ice Claws FOEs in them. When they go over a Chop point, they'll change the contents of the gathering node after 1 turn. The statistics in the next part of the data contains the data for the node BEFORE the Ice Claws ripped through it. The data contained in offsets 24 through 3C is after they've sliced up the point. (If you're wondering why there's a whole data section dedicated to the Ice Claws gimmick, it's leftovers from how EO4 handed its scripted gathering nodes.)

44: Header 3 (Indicates where the gathering tables start.)
48-4B: Tells the game to look at the next table instead if certain conditions are fulfilled. (Irrelevant for this part.)
4C: Chance to get the rare item.
50: Chance to get the uncommon item. (Actual chance is NOT EQUAL to the listed chance. Read the Gather Mechanics section for more details.)
54-55: Rare item ID.
56-57: Uncommon item ID.
58-59: Common item ID.
5C: Ambush Chance

Gather Mechanics:
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First, the game rolls for the ambush chance. If the check succeeds, you'll be ambushed once you're finished gathering. Either way, the game first rolls for the rare item. If that check fails, the game then rolls for the uncommon item. If that check fails, then you just get the common item. What this means in practice is that the listed chance to get the uncommon item is a little more than the actual chance to get it.

How to calculate the actual chance:

Actual Rare Chance = Same as listed chance.
Actual Uncommon Chance = (100 - Rare Chance) * Listed Uncommon Chance
Actual Common Chance = 100 - Actual Rare Chance + Actual Uncommon Chance.