Term IDoc stand for Intermediate Document and it is an SAP format widely used by non-SAP systems to connect with an SAP system.
There is a Portuguese soccer player and a Roman coach who don’t understand each other’s language. They need to talk about the game and English turns out to be a common ground. Portuguese still uses his native language and mentally translates English to understand it, he is able to have a conversation with the Roman coach. Idocs facilitates similar conversation between an SAP and non-SAP system. It works on the same principle – two systems share relevant keywords with filling language constructs that can be translated.
When two SAP systems are using Idoc, the transfer of data is done by ALE and when an SAP system uses Idoc to pass data to a non-SAP system (or vice versa), it is done by EDI. Apart from data sharing, it can also enable automation.
An idoc can be an Inbound Idoc or Outbound Idoc based on where the Idoc is generated and where is it flowing to. For example – ABC, a non-SAP system, passes data to ECC; the Idoc is generated in ABC and is coming into ECC and hence, is an Inbound Idoc with respect to ECC. The opposite – an Idoc which is generated in ECC and is coming into ABC – is an Outbound Idoc with respect to ECC.