The document discusses the Legacy System Migration Workbench (LSMW) in SAP, which is a tool used to transfer data from non-SAP legacy systems to an SAP R/3 system. It describes the basic principles, features, and steps of using LSMW, including maintaining source structures and fields, mapping fields, importing and converting data, and displaying the results. The main steps are creating an LSMW project, mapping source and target structures and fields, importing legacy data files, and converting the data for use in SAP.