Technically, from what I understand, a "Zepp" is a 1/2WL wire end-fed with 
1/4WL of parallel feedline. Of course any odd multiple of 1/4WL will work.

A "Center-Fed Zepp" is a one wavelength dipole usually fed with an odd 
multiple of 1/4WL of parallel feedline to achieve system resonance without a 
tuner.

An "Extended Zepp" is a 5/8WL end-fed antenna - same as the popular 2m 5/8WL 
vertical.

An "Extended Double Zepp" is a 1.25WL center-fed dipole usually fed with a 
matching section of ~1/5WL parallel line plus any number of 1/2WLs.

Technically, all Zepps are single-frequency antennas. You can use a "Center 
Fed Zepp" on other frequencies but it is no longer technically a Center-Fed 
Zepp. You can
use an End-Fed Zepp on other frequencies but it is no longer technically an 
EDZ.

The balluns used in a lot of Zepps are really pretty inefficient.  You're 
much better, if at all possible, using a balanced-line tuner into a dipole 
fed with open-line.

http://www.qsl.net/ta1dx/amator/practical_dipole_antenna.htm

Steve, K8SP