For purposes of this Part—

"arrangement"

means any transaction, operation, scheme, agreement or understanding (whether enforceable or not), including all steps therein or parts thereof, and includes any of the foregoing involving the alienation of property;

"avoidance arrangement"

means any arrangement that, but for this Part, results in a tax benefit;

"impermissible avoidance arrangement"

means any avoidance arrangement described in section 80A;

"party"

means any—

who participates or takes part in an arrangement;

"tax"

includes any tax, levy or duty imposed by this Act or any other Act administered by the Commissioner;