Welcome to permies Brennalyn
While I understand the PDC thing is quite majorly protected, Holzer's methods
can be used in '
permaculture course XYZ', which sounds like what you're asking about. There's often confusion over what the 'C' in PDC means, so just in case...
Someone'll be along with some useful info about courses
A PDC (Permaculture Design Certificate)
must cover the main elements in
Bill Mollison's
Permaculture Designer's Manual, and as Saybian says, PDCs are really about big-picture design. Say, capturing
water in the landscape, designing homes for maximum
energy efficiency in climate X etc, etc.
As far as I know, Holzer does not have a PDC and all teachers of PDCs must have one themselves.
Also, where are you, and would you travel far for the 'right' course? Here's a how-to for adding location info:
https://permies.com/t/7677/tinkering-site/Please-add-your-location-zone#134482
Apologies if this is confusing