[S02] sigils are not available as prefix operators

std and the compilers do not implement it, neither is it use in the spec or
the test suilte

S02-bits.pod

@@ -14,7 +14,7 @@ Synopsis 2: Bits and Pieces
     Created: 10 Aug 2004
 
     Last Modified: 09 Apr 2012
-    Version: 255
+    Version: 256
 
 This document summarizes Apocalypse 2, which covers small-scale
 lexical items and typological issues.  (These Synopses also contain
@@ -2074,8 +2074,8 @@ single-character context specifiers such as + for numbers and ~ for strings:
     %x{~f()}  =  %y{g()};   # string item context for f(), list context for g()
     %x{f()}   =  %y{~g()};  # list context for f(), string item context for g()
 
-Sigils used either as functions or as list prefix operators also
-force context, so these also work:
+Sigils used as functions with parenthesis also force context, so these
+also work:
 
     @x[$(g())]         # item context for g()
     %x{$(g())}         # item context for g()