The field map is a line by line list saying what each field in the old system becomes in the new one. It is the blueprint for the entire job, it is the document the client signs, and nothing loads until it is agreed. This article covers what goes in each row, how to handle fields with nowhere to go, and the ID rule that keeps records and documents together.
The short version. One row per source field. Every row ends in a home, a transformation, or a written decision that it does not travel.
What a mapping row contains
Before the list: what do you think is the column people forget, that causes the most arguments later?
Column
