In the original FFII (and FFIV) the Immune Byte was bugged in that the character who had an item with the Immune Bit equipped, was given 99% Evasion and if it was removed they had a lingering x4 Weakness to Fire and Ice. This patch fixes both behaviors, for the Immune byte-99% Evasion fix the storing of the Immune Byte "temporarily" is no longer put in the same place as Evasion and is instead moved to a free section of RAM where it does not interfere with later Evasion calculations. On that same note the game never properly decrements the bits that contain xr Weaknesses by a bizarre choice of design and oversight, it only took two NOPs (which doesn't effect anything else at all) to fix that behavior.
This only really serves purpose for modders who may want to add other Elemental Immune equipment or those who Really want the Glass Mask and Adamant Armor to not unbalance the game (granted the Adamant Armor does a good enough job of that as is)
Here is my first submission then, the Immune Byte Fix.
As you can imagine it's a little difficult to get a picture of this in action.
We have EVEN MORE themes now, but some old ones are gone...