This concept also available in datastage parallel jobs only. Through this concept even though if source contains no columns then run time column may propagate and treat the column is available in the source.
How to run the job through RCP:
Go to the data stage administrator ->go to the properties->in general click on enable run time column propagation in parallel jobs ->click ok->close.
Go to data stage designer ->select a required job->go to properties->click on enable run time column propagation for new links.