hi,
In case they are errors that you can/ want to capture 
before proceeding to the session. you can

capture it in the end_of_record area for each record and 
move it to an internal table which can

then be downloaded in the end_of_processing.

Example : You have a loaded material master with the legacy 
material number in BISMT field in

MARA. Let's say you now want to load your inventory. In the 
LSMW for the inventory load you

can do a select and get teh SAP material number for the 
legacy material number provided to you.

In this select if you do not find the SAP material number 
for one material(may be it errored out

during material master load for instance) you can move this 
record to an internal table and in the

processing block when all such errrors have been collected 
in the internal table then you can

download it to your presentation server so you can report 
it to your business users to fix. This is

my preferred method of loading data. Sure it will error out 
int eh batch session as a valid SAP

material number is not provided but then you can never fix 
it automatically. you will have to

process tem in the foreground or in errors mode and this 
invoves a lot of time and developers

intervention. In my way developers intervention is limited. 
A report is generated and then

business will fix the data and the delta loades will have 
to be loaded.

Here's the sample code :

Material Number

BINS-MATNR ()
RLBES-MATNR = BINS-MATNR.
clear RLBES-MATNR.
select single matnr into RLBES-MATNR from MARA
where BISMT = BINS-MATNR.
IF SY-SUBRC 0.
RLBES-matnr = BINS-MATNR.
MOVE-CORRESPONDING BINS TO err_file.
MOVE 'Material not created' TO err_file-error.
APPEND err_file.
WRITE : 'NO MATERIAL'.
skip_record.
endif.

__END_OF_PROCESSING__

FUNCTION 'GUI_DOWNLOAD'
EXPORTING
FILENAME = error_file_name
TABLES
DATA_TAB = err_file.
IF SY-SUBRC 0.

MESSAGE ID SY-MSGID TYPE SY-MSGTY NUMBER SY-MSGNO
WITH SY-MSGV1 SY-MSGV2 SY-MSGV3 SY-MSGV4.
ENDIF.

This example used GUI_DOWNLOAD . Ofcourse this is now not 
recommended so you can use the

latest FMs for download.
Thank you.
Regards.