Going the the CLDR utilities properties tool here:
When you select something (like Bidi_Class Arabic Letter) it goes here:
http://unicode.org/cldr/utility/list-unicodeset.jsp?a=[:Bidi_Class%20(bc)=Arabic_Letter:] and returns '0 code points' and generates 'Illegal property: Bidi_Class (bc)'.
The expected results is a long list of Arabic, Syriac, Thaana, etc. code points – some 1,436 code points.
A workaround seems to be to remove the '(bc)' and results will show. Alternatively, clicking the 'AL' instead of 'Arabic_Letter', the properties search works.
In speaking with Rick McGowan, he suggests there is a bug in the JSP code that inserts the parenthesis parts, but doesn't seem to process these correctly (assuming they are desired as part of the query). The bug seems to affect other properties with parts in parenthesis, e.g., 'Lowercase (Lower)'.