Hi Sandeep,
I am not sure if I understood your problem correctly.
As you mentioned in one of your comment that you want to know how to read this data into SAP? Answer is you need to create an internal table with maximum(out of header and item data length) length and use FM GUI_UPLOAD. You'll get data in SAP.
Then based on Identifier(H/L), you can SPLIT it and get exact data.
Please let me know if my understanding is not correct.
Regards,
Shyam