Even if the employer has clarified that a memorandum of understanding must not be binding by qualifying the draft concept as „contractive“, this may be insufficient if subsequent measures demonstrate otherwise. With regard to RTS Flexible Systems, it was essential that the parties behaved as if there was an effective binding contract. Work has been done, payments have been made and both parties have agreed on a change to the program. They implicitly accepted the existence of a contract and therefore waived the requirement of „the subject matter of the contract“. The plain language used in the Memorandum of Understanding shows the intention of the parties to be bound to it. The MoU contained voluminous language that only makes sense in the context of a binding contractual obligation. With regard to the obligations of the parties, the Memorandum of Understanding used mandatory terms such as „shall“ and „becomes“ in all its provisions, indicating its binding nature. There is no explanation as to why the parties would use such a mandatory language to refer to obligations if they were only optional or prective. In addition, the Memorandum of Understanding states that, by signing, the parties „indicate that. Approval of the terms of this [Statement of Intent]“ This portends a binding agreement. Forest City does not explain why a document that did not create binding rights would provide for the end of „rights below“ or why a document that does not create binding obligations would nevertheless provide for their „automatic release“. By letter of 17 April 2008, Forest City expressed its opposition to A.J.`s assertion.