What do you mean "last name"?
If you have two last names, then what?
If you have no last name, then what?
> Keeping them separate inevitably results in a convention to put company names in the last name field for corporations
If you only have a single field for name, this problem disappears.
Yes, but then you have to deal with the indexing/search problem instead.
What do you mean "last name"?
If you have two last names, then what?
If you have no last name, then what?
> Keeping them separate inevitably results in a convention to put company names in the last name field for corporations
If you only have a single field for name, this problem disappears.