For the purpose of this Part

(a) a "statement" is an oral or written expression, or conduct of a person intended by him as a substitute for oral or written expression;

(b) a "declarant" is a person who makes a statement;

(c) "hearsay evidence" is evidence of a statement, other than a statement made by a witness while testifying in the action at the trial, offered to prove the truth of the matter stated;

(d) a "hearsay statement" is a statement evidence of which is hearsay evidence;

(e) "unavailable as a witness" means that the declarant is:

(i) exempted or precluded on the ground of privilege from testifying concerning the matter to which his statement is relevant; or

(ii) disqualified as a witness from testifying to the matter; or

(iii) dead or unable to attend or testify at the trial because of a then existing physical or mental condition; or

(iv) absent from the trial and the court is unable to compel his attendance by its process; or

(v) absent from the trial and the proponent of his statement has exercised reasonable diligence but has been unable to procure his attendance by the court's process; or,

(vi) in such a position that he cannot reasonably be expected in the circumstances (including the lapse of time since the statement was made) to have any, recollection of matters relevant to determining the accuracy of the statement in question.

(f) "available as a witness" means that the declarant is not unavailable as a witness.