How is an oxidation half-reaction written using the reduction potential chart? How is the oxidation potential voltage determined?

Oxidation half reaction is written as follows when using using reduction potential chart

example when using copper it is written as follows

CU2 + + 2e - - - > c (s) + 0.34v

oxidasation is the loos of electron hence copper oxidation potential is as follows

cu (s) - - > CU2 + + 2e - 0.34v