It would be wonderful if you could have SAS tell you the half width of a confidence interval for a proportion if given a coverage probability, true outcome proportion, and sample size in PROC POWER ONESAMPLEFREQ. This would be useful for choosing a sample size for a single-arm clinical trial.
onesamplefreq ci=wilson /* or exact, wald, etc. */
halfwidth = . /* want to solve for this! */
proportion = .5 .7 .85
ntotal = 25 50 75
probwidth = .95;