The other technique for creating a reusable transformation is to promote an existing transformation within a mapping. By checking the Make Reusable option in the Edit Transformations dialog box, you instruct the Designer to promote the transformation and create an instance of it in the mapping.
To promote a non-reusable transformation:
In the Designer, open a mapping and double-click the title bar of the transformation you want to promote.
Select the Make Reusable option.
When prompted whether you are sure you want to promote the transformation, click Yes.
Click OK to return to the mapping.
Now, when you look at the list of reusable transformations in the folder you are working in, the newly promoted transformation appears in this list.