In this chapter:
(a) "Principal office" means a principal office of the corporation, unincorporated association, or partnership in this state in which the decision makers for the organization within this state conduct the daily affairs of the organization. The mere presence of an agency or representative does not establish a principal office.
(b) "Proper venue" means:
(1) the venue required by the mandatory provisions of Subchapter B or another statute prescribing mandatory venue; or
(2) if Subdivision (1) does not apply, the venue provided by this subchapter or Subchapter C.