[sdiy] I'm confused

[J. Larry Hendry]

I was looking at some TL082 op amps.  They look like they might be pretty
decent general purpose amps.  However, like many of these ICs, they have a
variety of suffixes at the end of the number.  I can see some different ones
for different packages. But, I see a variety of suffixes even for the DIP 8
package.  In particular, I see IP as a prefix.  I have found these surplus
for about 1/3 the regular price.  So, I wonder the significance of the
prefix (not just on this one).  Anyone care to shed some light on this for
me or direct me to a good FAQ or other reading material on the subject?  Are
spec "rejects" the ones that end up on the surplus market?

Thanks
Larry H.