# Mapping Input Specification

This step acts as a place-holder in a Mapping sub-transformation. It describes the places (0 or more) in the mapping where input is expected to occur. You can think of it as a special input step that receives data from its parent transformation.

![Mapping Input Specification dialog](/files/NVpPMvPhyG733Dw0b3OZ)

To help you create and design the sub-transformation, this dialog box includes the required input fields for the sub-transformation.


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