Abbreviations etc (in the data files)
HD reference numbers are those created by Derek Holliday & Brian Pask for their 1978 study of Hey-Dolphin machines:
HDT = trial machine
HDM = medium speed machine
HDL = hand operated version of 'M' machine
HDE = improved version of 'M' machine (listed by the manufacturer as an 'ER' model)
HDF = 'Flier' high speed machine
Type of die:
s.c. = single circle
d.c. = double circle
Canceller element is 5 wavy lines (5W) unless stated otherwise:
7W = 7 wavy lines
7S-1R = 7 straight bars with numeral "1" embedded towards right-hand side
7W-1L-C = 7 wavy lines with numeral "1" embedded at left-hand side and "C" embedded lower left
6S = 6 straight bars
Slogans were also extensively used (not itemised here - recommendation is to refer to specialist slogan listings)
Dates annotated "HP" are from Holliday/Pask but exact die inscription and punctuation are not known
Die descriptions (e.g. 7mm gap between L and 1) - measurements are in a straight line between specified points