Notify rule

Hi!
I trying to create rule for update notifing:

CREATE OR REPLACE RULE "ttt_NotifyU" AS
ON UPDATE TO "ttt" DO
NOTIFY "ttt", '88';
this work.

But this
CREATE OR REPLACE RULE "ttt_NotifyU" AS
ON UPDATE TO "ttt" DO
NOTIFY "ttt", NEW."id";
don't (syntax error),
NOTIFY "ttt", CAST(NEW."id" as text)
too.

Q: How can I send tuple id (integer primary key) via notify using Rule?
Target is erasing deprecated tuples from application's cache.

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