A comment about SPF. The Honolulu newspaper of about a week and a half ago had a story about sunscreens and advertised SPF ratings. Essentially the story said that the advertised ratings were greatly inflated. Most of the "SPF40/50/??" were in fact about SPF 8. But, if I recall correctly, SPF 8 reduced damaging exposure about 85%.
No mention of clothing ratings but before I believed any of the marketing claims I'd want to see some independent testing results before I believed them.