In releases prior to SAP NetWeaver 7.0 (up to BW 3.x), there was just one data flow approach between two persistent objects (source and target): a transfer rule, an InfoSource, and an update rule.
As of SAP NetWeaver 7.0, the transformation assumes the functions of the transfer and update rules. You can generally use as many InfoSources as you want (or none at all) in the data flow between a source and target; each of these is linked to transformations.
The 3.x InfoSource is not used by the transformation. There is now a new type of InfoSource that replaces this.
General Practices with Migration
You can create a transformation using update rules or transfer rules. The corresponding 3.x InfoSource is converted into a (new) InfoSource in the process.
We recommend using automatic migration in most cases.
More information:Migrating Data Flows
For more information about migrating update rules, 3.x InfoSources, transfer rules and manually editing transformations after migration, seeMigrating Update Rules, 3.x InfoSources, and Transfer Rules