On 18/02/2013, Mark Proctor <mproctor(a)codehaus.org&gt; wrote: 5.1.1 permitted a binding to the field on which a constraint was based, e.g., Person( $a: age > 10 || $sa: sibling.age > 10 ) I'd say that field bindings must have some attraction in addition to their heritage. Note that Lisp-ish CLIPS can access fact properties based on a binding to the fact and the field name, but field bindings are there all the same. (And, just because something's been used in another language doesn't mean it's bad and must be avoided like the plague.) Simple field bindings is the one feature that permits me to write rules tersely, lets me introduce an abbreviation for lengthy factref.nameOfTheField and - if used consistently - signals a pattern's dependency on some fact field. And what about the positional bindings? I guess they are here to stay. If so, it would be bizarre to the extreme if you could write Foo( $a, $b; ) but not Foo( $a: a, $b: b ) Consider: a feature requiring annotations on the unordered fields Java class is permitted, but a very similar feature NOT requiring annotations is not...? Summary: Retain simple forms for binding "on the fly" to a field. IMHO, there's no need to go overboard to permit it anywhere in complex expressions (Edson's worry). -W