You can create a session to run multiple source files for one source instance in the mapping. You might use this feature if, for example, your company collects data at several locations which you then want to move through the same session. When you create a mapping to use multiple source files for one source instance, the properties of all files must exactly match the source definition.=0D.
When we use Flat file as a source we give the path of directory where we store the file in Workflow.
But if we want data from multiple flat files then we put the names of all flat files in a single file called as file list.
In workflow mapping we give the path of list file and mark the source file type as Indirect as we are indirectly accessing all the flat files.