Additional letters of support (LOS) are personal handwritten letters on stationary written by an alumna endorsing a PNM (Potential New Member) whom they know personally for membership in their sorority house. “Letters of Support” differ from Recommendations/References in that they are not on the official sorority recruitment information form and are often sent to the chapter either alone or as a supplement to the recruitment information form. These LOS are closer to your common recommendation "letter" than they are to RIFs/Recs. A LOS is typically a complement to, rather than a replacement of, a standard RIF.