Zero elevation vs zero suppression

Sounds like homework, but here's a link to a good book that would help you.

http://books.google.com/books?id=TxKynbyaIAMC&pg=PA530&lpg=PA530&dq=%22zero+suppression%22+elevation&source=web&ots=jvrdMKbCwO&sig=pyLwE9Flhapa4CR0vrhgvZLfwoI&hl=en&sa=X&oi=book_result&resnum=3&ct=result

simply a bullshit answer

The zero refers to the lowest possible output of a device, for example if you have a pressure sensor that is 0 to 15 psi range with a 0 to 10 volt output and you elevate the zero by 5 psi you then have a 5 to 15 psi range pressure sensor with a 0 to 10 V output.

Zero elevation is the ability to calibrate an instrument, usually deltr pressure tansmitter so its lower range value is a negative value. i.e. -100 to 0 or -25 to 100 etc.