A more thorough explanation:

A DATO

a dato (ay day-toh) is a Latin term used in law that means "from the date."

It is also known as a datu.

1. The contract will be effective a dato of signing.

2. The lease agreement will commence a datu of the first day of the month.

The examples show how a dato is used to indicate the starting point or effective date of a contract or agreement. In the first example, the contract will be effective from the date it was signed. In the second example, the lease agreement will commence from the first day of the month.