It can be very useful to see how a particular piece of data flows through your data flow. Field tracing allows you to track the flow of your data by typing or choosing a field name from the Trace field drop-down at the top-right of the screen. Any pin or wire which contains this field will be highlighted in the data flow:
You can also choose a field to trace from the data viewer by selecting Trace from the column menu button.
The appropriate field will be traced through the data flow.
To remove any field trace from the data flow, choose the blank option at the top of the Trace Field drop-down list.