As used in this part, the term:

(a) Corresponding principal officers means any person or persons performing or authorized to perform, principal executive functions corresponding to those of president and treasurer of any entity engaged in whole or in part in the performance of the activities described in section 203(b) of the Labor-Management Reporting and Disclosure Act of 1959.

(b) Fiscal year means the calendar year or other period of 12 consecutive calendar months, on the basis of which financial accounts are kept by a person. Where a person designates a new fiscal year prior to the expiration of a previously established fiscal year period, the resultant period of less than 12 consecutive calendar months, and thereafter the newly established fiscal year, shall in that order constitute the fiscal years.

(c) Undertake means not only the performing of activities, but also the agreeing to perform them or to have them performed.

(d) A direct or indirect party to an agreement or arrangement includes persons who have secured the services of another or of others in connection with an agreement or arrangement of the type referred to in § 406.2 as well as persons who have undertaken activities at the behest of another or of others with knowledge or reason to believe that they are undertaken as a result of an agreement or arrangement between an employer and any other person, except bona fide regular officers, supervisors or employees of their employer to the extent to which they undertook to perform services as such bona fide regular officers, supervisors or employees of their employer.