fill in fields by criteria in continuous form

[cosmicslop]

I would like to be able to fill in some text fields in a continuous form. I have one number that is unique, the fields that should be filled in automaticaly could be already filled in or be blank. the unique number looks like this zee001234a then zee001234b, etc. now i would want the user to be able to fill in on the record zee001234a for exemple a date and this date should automaticaly be filled in on the record zee001234b I persume a query on a left trim of the zee nr somehow should do the trick. does anybody outthere understand what I am wabbling about?