Usually you don't get the entire sub-screen's data such that a blank versus null distinction wouldn't help. You can't "half submit" a dialog or sub-screen on the vast majority of systems I ever worked with it, and one adds time-stamps to critical sub-screens if they can.
Maybe you encountered a specific product's edge-case where it helps, but I'd rather trade away 9 other headaches to get your edge case headache. It may be the case that Product X doesn't allow time-stamps, but should we gum up all strings to make just Product X happy? I don't see how the tradeoff math favors that. Plus, it encourages bad designs by plugging problems with funny non-printable codes. Let's not enable slop-heads.
Re: but for other datatypes
For the purpose of this discussion I'm limiting it to strings, where the majority of null-related headaches are found in my experience.
Maybe you encountered a specific product's edge-case where it helps, but I'd rather trade away 9 other headaches to get your edge case headache. It may be the case that Product X doesn't allow time-stamps, but should we gum up all strings to make just Product X happy? I don't see how the tradeoff math favors that. Plus, it encourages bad designs by plugging problems with funny non-printable codes. Let's not enable slop-heads.
Re: but for other datatypes
For the purpose of this discussion I'm limiting it to strings, where the majority of null-related headaches are found in my experience.