This is nothing but Pivot Point Formula. The pivot point formula is like this:

H=Prev day High, L=Prev day Low and C=Prev day Close.

Using these calculate the PIVOT POINT(P) as follows:

P=(H+L+C)/3

From this Pivot Point(P) calculate the resistance levels as follows:

First resistance level (R1)

R1=(2 X P)-L

Now you can see 2 X P=(H+L+C) X 2/3=(H+L+C) X 0.67 which is given as Z by Abdur in his post. Therefore, the first resistance level R1 is same as Z - L as given by Abdur.

Similarly, the first support level (S1) is calculated as:

S1=(2 X P) - H = (H+L+C)X2/3 - H = (H+L+C)X0.67 - H

This is same as Z-H as given by Abdur.

The second Resistance (R2) and support (S2) Levels are calculated as:

S2 = P - (H - L) = P - (R1 - S1)

R2 = P + (H - L) = P + (R1 - S1)

These are not given by Abdur.

You can get full details of Pivot Points and how to trade with them (intra-day) by following the link:

http://www.investopedia.com/articles/technical/04/041404.asp
Abdur has given the Pivot Point formula in a different way by using different letters like Z, PB etc. It is nothing new. Pivot Point trading is well known technique and is known from a long time. It is not a formula discovered by Abdur. It would have been better if Abdur had mentioned about the source of his formula.

-Anant