Sounds to me like they are referring to an internal list of positions that they are working on filling. I work for home health agencies. Each one has their unique list of cases that they are trying to staff. Occasionally, they will have a case that is shared with another agency but that is not the norm. It would be impossible for each travel agency to staff every open position. The employers usually deal with only certain agencies to staff their openings. Sometimes more than one agency will have the same openings for that employer. You would fill the position based on which agency you are working for. Some nurses will find out what each agency offers, and go with the agency that has the best package. Good luck with your job hunting.