This file assigns the position for characters in party at the beginning of specified part of game.
The first column is filled by the identifiers of selected position feature. This indicates also what part of game uses these values like tutorial or normalgame.
First row contains numbers that indicate the number of party member.
Other rows contain of numbers that are coordinates described by identifier in first column.
In BG2 ToB we have:

2DA V1.0
0
                    1       2       3       4       5       6
START_XPOS          3741    3585    3532    3374    3824    3889
START_YPOS          2801    2917    2956    3068    2447    2479
START_XPOS_TUTORIAL 607     607     607     607     607     607 
START_YPOS_TUTORIAL 660     607     607     607     607     607 
START_XPOS_MP       1300    1300    1300    1300    1300    1300 
START_YPOS_MP       1840    1840    1840    1840    1840    1840