If you would like to see a different description for 'E-Mail or Username' when logging in, you can easily customize this text:
To do this, simply go to the administration area and navigate to Settings -> Texts -> Username description. Enter your text here, e.g. "Employee ID".
On the login page, the text should have already changed:
Please note that these changes may take up to 10 minutes to take effect.
Please wait... it will take a second!