Here it is word for word from the IBT Constitution.
Article 12 page 89(no I didn't make that up!!)
Section 1(a). When any difficulty or dispute arises
between the members of any Local Union and their
employers, it shall be the duty of the officers of such
Local Union to use every possible means of achieving a
settlement or resolution of the difficulty or dispute
through the processes of collective bargaining.
(b). Agreements shall either be accepted by a majori-
ty vote of those members involved in negotiations and
voting, or a majority of such members shall direct fur-
ther negotiations before a final vote on the employer’s
offer is taken, as directed by the Local Union Executive
Board. During negotiations, the Local Union Executive
Board may order a secret ballot strike vote to be taken
and when, in the judgment of the Local Union Execu-
tive Board, an employer has made a final offer of settle-
ment, such offer must be submitted to the involved
membership for a secret ballot vote as hereinafter
provided:
(1) If at least one half of the members eligible to vote
cast valid ballots, then a cumulative majority of those vot-
ing in favor of the final offer shall result in acceptance of
such offer; and a cumulative majority of those voting
against acceptance of the final offer shall authorize a strike
without any additional vote being necessary for such strike
authorization. In the event of a tie vote on either a motion
to accept a final offer or to strike, the Local Union
Executive Board shall conduct a second vote. If the result
of the second vote is a tie, the Local Union Executive Board
shall have the discretion to either accept the final offer or
reject the final offer and authorize a strike at such time as it
determines.
(2) If less than half of the eligible members cast valid
ballots, then a two-thirds (2/3) vote of those voting shall
be required to reject such final offer and to authorize a
strike. The failure of such membership to reject the final
offer and to authorize a strike as herein provided shall
require the Local Union Executive Board to accept such
final offer or such additional provisions as can be nego-
tiated by it.
When the final offer has been rejected in accordance
with this Section, it shall constitute authorization for a
strike at such time and under such terms and conditions as
the Local Union Executive Board may determine.
Any question arising from the application or inter-
pretation of this Section shall be decided by the General
President whose decision shall be final