SAP Adapter Use routing rules or maps

When receiving an IDOC into IS from SAP during the definition phase, I was told to use “mappings” instead of “routing rules”. Is it true that routing rules are going to be deprecated in the near future?

If so, can anyone explain how to create a map. All that I know is you must define your map prior to initiating something coming into IS or it will default to a routing rule.

The SAP adapter documentation for 4.6 only covers routing rules.

Thank you.