Anyone know what this code is doing?

Question

Howdy,
Don't suppose ya know what this code could be doing:
TABLES:  nast,
        *nast.
  SELECT * FROM  *nast
         WHERE  kappl       = nast-kappl
         AND    objky       = nast-objky
         AND    kschl       = nast-kschl
         AND    spras       = nast-spras
         AND    parnr       = nast-parnr
         AND    parvw       = nast-parvw.
    IF *nast-vstat = 1.
      processed = 'X'.
    ENDIF.
  ENDSELECT.
  CHECK processed NE 'X'.
Its got me stumped! what on earth is *NAST?
Are we simply looping through all the entries in NAST???
Basically I came across this code because I am trying to write a program that gets triggered when the user saves a Debit note.
My program should then take the billing document number that was saved and use it to create a credit memo request, but finding the billing document number was a pain and someone told me that I had to use NAST or something...
ANyhow, I came a cross the following code but it doesn't make sense...
I think it should be
TABLES:  nast.
data: wa_nast type NAST.
  SELECT single * FROM  nast into wa_nast
         WHERE  kappl       = nast-kappl
         AND    objky       = nast-objky
         AND    kschl       = nast-kschl
         AND    spras       = nast-spras
         AND    parnr       = nast-parnr
         AND    parvw       = nast-parvw.
    IF nast-vstat = 1.
      processed = 'X'.
    ENDIF.
What do you all think?????

Answer 1

Thanks Rich,
May be you are right or may be I didn't amke myself clear.
I think my program will be connected to the output type via transaction NACE. Then whenever the user saves a debit memo it will trigger the output type and this should then trigger my program to produce the BDC based on the billing document number in the debit memo.
I thought this would be passed into nast-objkey and I thought I would write an entry routine that could be placed in NACE that access my program.
AM I correct in thinking that this would work????