The nucleus — Use

What information is given by the nuclide notation ^A_Z X, and how is it used?

In ^A_Z X, X is the chemical symbol of the element, Z (written lower left) is the proton number - the number of protons in the nucleus, and A (written upper left) is the nucleon number - the total number of protons and neutrons in the nucleus. For example, ^12_6 C represents a carbon nucleus with 6 protons and 12 nucleons in total, so it also has 6 neutrons (A - Z).