A start date is the day the contract activities begin. It is actually another term for a date of entry into force. While we recommend using the term validity date, you can see the start date of the validity period from time to time, especially for residential real estate rental contracts. The parties may set a date of entry into force which shall take place before the execution of the contract. For example, to collect royalties or payments retroactively to a past date. Again, Ken argues that it is clearer to use the concept of “date of agreement” and to specifically define the periods of rights and obligations that deviate from that date. In practice, it may be more convenient to set the work date for all rights and obligations rather than to set each of them individually. If you fail to comply with your treaty obligations after that date, the other parties can now sue you for infringement. It is important to note the date of entry into force of the treaty, as you need to know when your commitments will begin….