Per section 24 of the spec, using regular expression constructs that are not common to both ICU and Java 7 in a DFDL regular expression should result in a schema definition error. Instead, I am seeing a ClassCastException.

java.lang.ClassCastException: edu.illinois.ncsa.daffodil.processors.InfosetDocument cannot be cast to edu.illinois.ncsa.daffodil.processors.InfosetElement
[error] at edu.illinois.ncsa.daffodil.processors.PState.parentElement(PState.scala:222)
[error] at edu.illinois.ncsa.daffodil.processors.PState.getContext(PState.scala:162)
[error] at edu.illinois.ncsa.daffodil.processors.PState.SDE(PState.scala:193)

See tests in daffodil-test/src/test/scala-debug/edu/illinois/ncsa/daffodil/section07/assertions/TestAssertionsDebug.scala