What do the journal transaction types mean

I see transaction types 1, 4, and 5. I've looked in the documentation what do these mean?

Journal 

Transaction Types

1 = Actuals

2 = Carry Forward Actuals (used in Open Year)

3 = Carry Forward Encumbrance (used in Open Year)

4 = Encumbrances

5 = Budget

6 = Carry Forward Budget

The values 2, 3 and 6 are set in Open Year to force GLJNLPST to set the Budget Code to 2 to indicate carry forward amounts. The transaction types are then changed to 1, 4 and 5, respectively.