Earthlings, imagine this, if you will:
In field one : a start date and time
In field two : end date and time
In field three : A calculated field to express the duration between fields one and two in hh:mm.
All good to this point.
However, in field four I want to allow text inputting if field three reports a total that is equal to or greater than 24 hours. But if it's smaller than 24 hours either inputting should not be allowed or the field should automatically populate with: 'Not required'.
I'm guessing this can be done in Access but no amount reading around this morning has shown me how. And to be honest, it's sapping my morale.
Guidance on how to achieve this, preferably described in terms that a relative imbecile cand make sense of, would be deeply appreciated.