The CONECA doubled die numbering system is made up
of five elements: (WH-1-O-II-C)
Prefield. Indicating level of die involvement.
indicates that the same doubling occurs on more than 1 year on a
given denomination. The best example is the reverse of the
1972-74 and 1977-78 Eisenhower Dollars. Approximately half of
the 1972 coins and all the coins of the other dates exhibit a
tripled die that can be seen on the designer's initials and the
AR of DOLLAR. The same tripled master die was used in
Master Die Doubling
indicates that several working dies of a given year and
denomination exhibit the same doubling. In the past, this has
crossed mint lines to affect coins from all mints. The best
example is the 1944 Jefferson nickel. Now that mintmarks are being
placed on the master dies, it will be more likely that master
die doubling will only affect coins from one mint. It is now
possible to have master die doubling from two or more mints for
a given year and denomination that are not even of the same
class, let alone with similar appearance.
Working Hub Doubling
indicates that several dies of a given year and denomination
exhibit the same doubling. In the past, this may or may not
have crossed mint lines. Now, because the master die bears the
mintmark, it is restricted to one mint.
(PR) - indicates that the
doubled die is on a proof coin rather than a circulation or
number or listing number. The die number starts at 1 and
increments by 1 for each new listing of a date and mintmark for
a given denomination. The die number for a master die or a
series listing is the same for each mint and year involved.
Obverse or Reverse (O, R).
Class of doubling in Roman Numerals. Hybrid classes are
indicated with a +.
Class I - Rotated
Class II -
Distorted Hub Doubling.
Class III -
Design Hub Doubling.
Class IV -
Offset Hub Doubling.
Class V - Pivoted
Class VI -
Distended Hub Doubling.
Class VII -
Modified Hub Doubling.
Class VIII -
Tilted Hub Doubling.
Where appropriate, the direction of the
doubling and the number of hubbings, if more than two.
C - toward the center
CCW - counter-clockwise
CW - clockwise
E - toward the edge
K - clock position for the pivot point
(3) - tripled die
(4) - quadrupled die
(M) - Multiple hubbed die