What does LEFT JOIN … ON TRUE means and what is used for?
For example:

|LEFT JOIN TTDebtsCalculation AS DebtsCalculation
|ON TRUE

This means that all rows of joined table will be joined to all rows of the result of tables joined above:
Table 1:

1 1
2 2

3 3
4 4

1 1 3 3
1 1 4 4
2 2 3 3
2 2 4 4