An Agreement of Participation with a pension fund does not stand alone but must be read subject to and in conjunction with the fund's rules as validly amended from time to time under the Pension Funds Act. Where fund rules provide for automatic annual increases in employer contributions up to a specified minimum, and those rules are incorporated into the Agreement of Participation, the employer is bound by such increases even if the initial agreement specified a lower rate. A subsequent amendment pegging contributions to those 'specified in the AGREEMENT OF PARTICIPATION' does not freeze contributions at the originally stated rate where, by the time of the amendment, the contribution rate had already increased pursuant to the automatic escalation provisions in the rules. Pension fund rules have binding statutory force under section 13 of the Pension Funds Act 24 of 1956 and must be interpreted according to ordinary principles of contractual and statutory interpretation, without inserting words, creating anomalies, or adopting unbusinesslike constructions.