INVOIC01/ INVOIC02 and function module
what I'm trying to do now is upload invoice information from CSV file to SAP via XI. So in XI the CSV file will be convert to IDOC structure and load to SAP. It's for SAP as buyer scenario. There are two IDOC types, INVOIC01 and INVOIC02, are they for inbound invoice and outbound invoice respectively? what's the difference? and which one should be used for this scenario?
Also, noticed there are three function modules related to inbound IDOC processing, IDOC_INPUT_INVOIC_MM, IDOC_INPUT_INVOIC_MRM and IDOC_INPUT_INVOIC_FI. What't the difference? and which one should be used to create invoices?
Thank you for your help!