How can I autopopulate a date field when data entered in another field?

[jant45441726]

I have a field named Value when data is entered I want a date field showing the date.

[George_Johnson]

What should happen if the field is later cleared? Or if the value is later changed?

[jant45441726]

The date field should be read only.

You have a point regarding the value field, I do not want the user the user to reenter.

Is there a way to validate that the user enter a number within a certain range: 240+/- 3, and get a warning if it is out of range?