mxspl***2da

This file defines the spell gaining tables per level.
Where:
First colunm is the PC's/NPC's level.
Columns 2-8 contain of number of spells that CRE should have on the specific level in their spell book (for other MXSPL***.2DA files there is different number of columns, like in  ranger's case we have only three columns or like in wizard's case we have 9 columns that corresponds to their capabilities to case the spells of specified levels.
In case of bard, ranger and paladin there is a possibility to add more levels of spells simply by adding columns in the proper 2DA file.
Note that the BG2 manual is incorrect in regards to the casting level for rangers and paladins. Rangers cast at a spell level 7 levels below their current level, while paladins cast at a spell level 8 below their current level. This casting level is not capped at 9.
In BG2 ToB we have (mxsplbrd.2da):
2DA V1.0
0
           1          2          3          4          5          6          
2          1          0          0          0          0          0          
3          2          0          0          0          0          0          
4          2          1          0          0          0          0          
5          3          1          0          0          0          0          
6          3          2          0          0          0          0          
7          3          2          1          0          0          0          
8          3          3          1          0          0          0          
9          3          3          2          0          0          0          
10         3          3          2          1          0          0          
11         3          3          3          1          0          0          
12         3          3          3          2          0          0          
13         3          3          3          2          1          0          
14         3          3          3          3          1          0          
15         3          3          3          3          2          0          
16         4          3          3          3          2          1          
17         4          4          3          3          3          1          
18         4          4          4          3          3          2          
19         4          4          4          4          3          2          
20         4          4          4          4          4          3          
21         5          4          4          4          4          3          
22         5          5          4          4          4          3          
23         5          5          5          4          4          3          
24         5          5          5          4          4          3          
25         5          5          5          5          4          3          
26         5          5          5          5          4          3          
27         5          5          5          5          4          3          
28         5          5          5          5          5          3          
29         5          5          5          5          5          3          
30         5          5          5          5          5          4          
31         5          5          5          5          5          4          
32         5          5          5          5          5          4          
33         5          5          5          5          5          4          
34         5          5          5          5          5          4          
35         5          5          5          5          5          4          
36         5          5          5          5          5          4          
37         5          5          5          5          5          4          
38         5          5          5          5          5          5          
39         5          5          5          5          5          5          
40         5          5          5          5          5          5          

mxsplwis.2da

This file is responsible for bonus priests (clerics and druids) spells because of their wisdom:
In BG2 ToB we have:
2DA V1.0
0
        1   2   3   4   5   6   7
13      1   0   0   0   0   0   0
14      2   0   0   0   0   0   0
15      2   1   0   0   0   0   0
16      2   2   0   0   0   0   0
17      2   2   1   0   0   0   0
18      2   2   1   1   0   0   0
19      3   2   1   2   0   0   0
20      3   3   1   3   0   0   0
21      3   3   2   3   1   0   0
22      3   3   2   4   2   0   0
23      3   3   2   4   4   0   0
24      3   3   2   4   4   2   0
25      3   3   2   4   4   3   1
Columns numerated from 1 to 7 indicates the priest spell book level
First column is the CRE's wisdom.
The crossing of them indicate how many bonus spells have priest creature with specified wisdom.

Description applies to:
mxsplbrd.2da - Bard
mxsplpal.2da - Paladin
mxsplprs.2da - Cleric/Druid
mxsplran.2da - Ranger
mxsplwiz.2da - Mage
mxsplsrc.2da - Sorcerer
mxsplwis.2da - Wisdom bonus spells