Inbound Purchase order to IDOC

Hi

I need to generate the inbound PO from  a source data

Source                  Target   

Header 1:1                                                            idoc
General 0..10                                                        E1EDk02    0..10
          Release Number 0..1                                             QUALF 0..1
                                                                                      BELNR  0...1
                                                                                       POSNR  0..1
map constant 011 >QUALF
map releasenumber >BELNR
I need to map POSNR value as below based no of times node General repeating
for 0 fist loop)  instance of  General-  POSNR will be mapped to  10
     1  second loop                                                                    20
     3                                                                                         30
     .
     .

     8                                                                                          90
     9                                                                                          100

Thanks for your help