I have a database that identifices species.

The idea is that if we know for sure what the Genus is (a Y/N field denotes this), we can pull the Family and Class out of another database. However, it's not always the case that we're sure the Genus is correct, and in that case we need to be able to manually enter the Family and Class

What's the best way to do this?

My first thought was a calculation (case KnownGenus=Y, Rel::Family,"") , but of course you can't modify calcuation fields.

the other idea I had was to put the above calcuation field *behind* a user editable field, but that might look ugly if the user doesn't change the data after KnownGenus is set to Y

I thought a little about lookups, but we'd really like to keep it a relationship so we don't have to worry about relookups if the master classification database changes

advice?

TIA

I always create a calc field in which data cannot be entered. This is where the "final" determination will show up.

Directly behind it is an entry field where the manual entry is done. Since the calc field has user entry disabled, when you click in the field you're actually clicking in the manual entry field behind it.

The calc field returns the calc if the manual entry field is empty; otherwise it returns the contents of the manual entry field.

In your case, you can have the calc field return the calc if "Yes" is checked, and the manual entry field if it isn't.

ok, that's what I was thinking of doing.

but what if:

"yes" is NOT checked, and the user inputs their own value in the entry field behind

then yes gets checked and the field in front changes to something else. won't I have a garbled mess with two non-empty fields on top of eachother?

I do something similiar. Have the calculation field with the default answer. Then have a second field, which is the manual field, that allows you to change it. Then I have a button, that is attached to a script that simply when pushed populates the manual simple text field with the calculated field. So, if I know that the manual field is the default field (or in your case Genius = "yes") then I push the button and populate the field. Otherwise if (Genius = "no") leave blank so user can type it whatever he wants. Of couse I just do not display the calculated field.