This assembly patch allows you to pull off things like "Marth's level cap is different than the rest of this team's". By altering the value at 0xD5C000 + N, you can change the maximum level that units of class ID N can reach.
If I want Lyn's lord class to have a level cap of 30, the following steps are taken:
Lyn's lord class has ID 0x3
The offset of this class's level cap is 0xD5C000 + 0x3 = 0xD5C003
30 in hex is 0x1E
so I go to 0xD5C003 in a hex editor and input value 0x1E
Now, any unit with the Lyn Lord class will cap his/her level at 30.
the patch itself is "impl.dmp"
right now it writes code to 0xD50000 and the table is located at 0xD5C000