Clarification on synthetic numerics and No values

Refs #2632

Author: JJ

doc/Type/Str.pod6

@@ -348,8 +348,9 @@ Only Unicode characters with property C<Nd>, as well as leading and trailing
 whitespace are allowed, with the special case of the empty string being coerced
 to C<0>. Synthetic codepoints (e.g. C<"7\x[308]">) are forbidden.
 
-While C<Nl> and C<No> characters can be used as numeric literals
-in the language, their conversion via C<Str.Numeric> will fail, by design.
+While C<Nl> and C<No> characters can be used as numeric literals in the
+language, their conversion via C<Str.Numeric> will fail, by design; the same
+will happen with synthetic numerics (composed of numbers and diacritic marks).
 See L«unival|/routine/unival» if you need to coerce such characters to
 C<Numeric>.
 
@@ -1128,8 +1129,10 @@ be parsed.
 
 While characters belonging to the Unicode categories C<Nl> (number letters)
 and C<No> (other numbers) can be used as numeric literals in the language,
-they will not be converted to a number by C<val>, by design.
-See L«unival|/routine/unival» if you need to convert such characters to
+they will not be converted to a number by C<val>, by design, and using C<val>
+ on them will produce a failure. The same will happen with synthetic numerics
+  (such as 7̈ )See L«unival|/routine/unival» if you need to convert such
+  characters to
 C<Numeric>.
 
 =head2 method Version