Item # where referenced on Pages 1-4. Where else in this application is this KSA referred to. For example, if Bronze Star was one of your KSAs, then you might reference, Item # 20 or 21, (i.e. see Avail Page, 1 in the Military.) For KSA's earned on the job your reference will most likely be to the jobs page, e.g. job3. For Educational KSA's, your reference will probably be to the Education page, e.g. 28 (Name of my second to the last college) Some private companies wont care about this blank. So dont waste a lot of time cross referencing every KSA to its source. Companies can always ask you this on the interview if you leave it out here, & they really want to know. Never-the-less, for a Federal Govt. application, they may require all this.