Autocomplete rule with global transfer taking previous salary

Summary:

Hello, I have a problem with a simple rule, what I need is simple, when an employee is undergoing a global transfer, I need to get their previous salary, for example, the employee has salary X before entering the global transfer screen , when it is on the screen, I need the autocomplete rule to look at the salary that is on the screen, in the salary section of the global transfer screen and check if it is equal to her salary before entering the screen, if so, send the message "Equal salaries, please do not make the change". The