how to understand &analysis script execute process in batch job?

hi ,expert,

   i have a batch job in ds4.1, and has one script A which call 3 sqlserver store procedures.

script :

# execute sp1

IF $GV_Process1 = 'Y'

   DS.DBO.SP1($LV_RETCODE ,$LV_ERROR);

# execute sp2

IF $GV_Process2 = 'Y'

   DS.DBO.SP2($LV_RETCODE ,$LV_ERROR);

# execute sp3

   DS.DBO.SP3($LV_RETCODE ,$LV_ERROR);

now , i want to know the script execute process,

1. the sql sp execute by order or by parallel execution for one script ?

if $GV_Process1 = 'Y' and $GV_Process2 = 'Y',  both of the sp1 and sp2 be executed, sp2 execute when sp1 finish? or parallel???

2. if sp1 occur error, then sp2 and sp3 can't be execute ?

3. if sp1 execute ok, sp2 occur error,  then sp3 can't be execute ? and how to rollback sp1 transcation in ds?

   i think ds can't rollback any transcation, right?

thanks in advance.