CORRECTION (RE-CORRECTED 7PM EDT, Oct. 6, 2014
   I have corrected a typo in "second post on Tarski". In the previously published  version, in the sentence

"AND (important!) we add to the axioms the statement, duly formalized, that for all w, if v is a variable and w is z preceded by an existential quantifier (Ev) and z contains no free variables different from v, then {Ref(w,y) = 1  ≡  (Ex) Ref(z,x)} & {(Ref(w,y) = 0  ≡ (Ex)(Ref(z,x)}."

a negation sign in front of the last quantifier was missing and the "=0" and "=1" were a slip of the brain.
This should have read:

"AND (important!) we add to the axioms the statement, duly formalized, that for all w, if v is a variable and w is z preceded by an existential quantifier (Ev) and z contains no free variables different from v, then {Ref(w,1)  ≡  (Ex) Ref(z,x)} & {(Ref(w,0)  ≡ - (Ex)(Ref(z,x)}."

This is now corrected and a mention-use problem a little further down (just before "What Field observed" has also been corrected.