PSSAs are Optional?

According to an article I read today at http://parentsacrossamerica.org/pennsylvania-standardized-tests-burden-schools-and-students/, Pennsylvania's System of School Assessment tests (PSSAs--Pennsylvania's version of NCLB's high stakes/standardized testing) are not mandatory.  Parents can choose to opt their child(ren) out of the testing.  "Under Pennsylvania Code Title 22 Chapter 4, section 4 (d)(5), parents have the right to opt out of testing for their children. The exemption is “religious,” but the Pennsylvania Department of Education confirmed this includes any moral, psychological, philosophical or even medical objection. The reason cannot be challenged."  (Michele Gray, Parents Across America.)  I'm interested to see how many other states have such provisions.  If you know, please share.