sas, combine, unknown code datasets observations

[user112a2]

I need help reading the below code. I am not sure what specific parts in this code are doing. For example, what does ( firstobs = 2 keep = DPD_CLOSE_OF_BUSINESS_DT rename = (DPD_CLOSE_OF_BUSINESS_DT = Next_COB_DT) ) do?
Also, what does ( obs = 1 drop = _all_ ); do? I have also not used Prev_COB_DT = ifn( first.SOR_LEASE_NBR, (.), lag(DPD_CLOSE_OF_BUSINESS_DT) ); before, what does this do? I am reading someone elses code, I wish I could provide more detail. If I find a solution, I will post it. Thanks for your help.

    Removed

[Kurt_Bremser]

A set statement like this:

set
  LETNOTRG.REQ_1_3_03 (
    firstobs = 2
    keep = DPD_CLOSE_OF_BUSINESS_DT
    rename = (DPD_CLOSE_OF_BUSINESS_DT = Next_COB_DT)
  )
  LETNOTRG.REQ_1_3_03 (
    obs = 1
    drop = _all_
  )
;

performs a "look-ahead" into the dataset by starting to read at observation 2, and preventing a premature eof by reading 1 observation without data (that's what the drop=_all_ does).

What puzzles me is that it tries to read the same dataset that it is creating, so my guess is that this won't work.

[Tom]

It is doing the opposite of LAG().  It is creating a variable that will have the value of a variable from the NEXT observation.

But it is probably using the wrong dataset.  It should be using the same dataset as in the first SET statement.