Hi Robert,
You bring up a good point, an issue thats not always clear. Indeed 32 bit is some 4 Billion count unless it is Signed, then its half + & -.
The PBP manual says Longs are treated as signed. Info on the web said that Epoch time was a signed value, but on the Epoch info web you can put bigger values than 2.5 billion in the calc date and get a future date in what should be the (-) values.
I think it just shows that you have to know the intended use and MIN and MAX values of what your working with.
I tried out incrementing a long when it rolls over from 2^31, it displays continued count using DEC, but using SDEC, it rolls to -2^31 then counts down minus on increment. I know thats what it should do, just makes it a little clearer.

This is with SDEC modifier:
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Don
amgen