Fig. 3 Illustration of the two oxidation rate regimes. 
The equation d02 + Ad0 =B(t+t) has two important limiting conditions:
1. One limiting case occurs for long oxidation times and we get
d02 = Bt
This is called Parabolic Law and B is the parabolic rate constant. This is diffusion-controlled case.
2. For short oxidation times we get
d0 = B(t+t) / A
This is called Linear Law and B/A is called the linear rate constant and it is a reaction-controlled case.