Knowledge Management

Question:
Hello all, I need to copy some header texts from my purchase requisition to the Purchase order when I am using the ME21N tx. Please, does somebody knows an user exit to do this? and how can I do it?
First, I was thinking to use some functions like SAVE_TEXT, but in this case, I need that the PO should be created first. So this way is not that I need.
Please, let me know your answers.
Thanks in advance.
Answer:
try Read_text
Answer:
I think READ_TEXT is not possible. I need to create a new text and it can be created using CREATE_TEXT or SAVE_TEXT.
My problem here, is that in both cases I am creating a PO with reference From a Purchase Requisition, but these functions only saves information when the PO is created.
Please, can somebody helps me?
regads.