On Wednesday, December 27, 2017 at 7:19:43 AM UTC-6, Sonny wrote:
On Wednesday, December 27, 2017 at 4:39:57 AM UTC-6, wrote:

I WAS TOLD THAT THE "D" WAS SHORT FOR " DRACHMA" - GREEK COIN

The D, as in 10D nail, means that, when learning how to use a hammer, learn how to hammer a nail (probably myself and others as an example), you miss the nail and dent the wood 10 times, before the nail is sufficiently sunk into the wood. Sic.

Sonny

i.e., a designation of/for a carpenter's/woodworker's learning curve.

Sonny