Zero Is Not the Same as Empty

Somewhere the code is evaluating zero and being equal to 'no value', which is not the same thing. I have a select form item with the following options structure:

;100:100% of the time;50:50% of the time;0:never

That first semicolon creates an empty option, but it has no value so I wouldn't expect it to show up in the results. This is the same as NULL or 'we don't know anything about this'. The last option explicity submits the value '0', which is a number and means we do know something: 'this person never does this'. It should show up in the results and in the Excel download.