Appendix C. Leadhead Codes
A.
Leadhead Grouping
Methods that have a first leadhead that is the same as one of the leadheads found in the Plain Course of Plain Bob or Grandsire have been assigned a code according to the order in which the leadheads occur in its Plain Course. They are a useful shorthand for communicating the Lead order of a Method.
Originally lowercase letters were ascribed and these were later extended with numbers to cover higher stages. In the Framework the codes associated with the letters p, q, r and s have been renumbered to include the leadheads previously omitted before the Differential classes were added.
Methods with Plain Bob leadheads are split into different leadhead groups according to the place notation (where n is the Stage) immediately before the leadhead as follows:
- Those with even Stages and a lead end place notation of 12 have codes a-f
- Those with even Stages and a lead end place notation of 1n have codes g-m
- Those with odd Stages and a lead end place notation of 12n have codes p-q
- Those with odd Stages and a lead end place notation of 1 have codes r-s
Methods with Grandsire leadheads whose hunt bells have the same path are split into different leadhead groups according to the place notation (where n is the Stage) immediately after the leadhead as follows:
- Those with odd Stages and a place notation of 3 following the leadhead have codes a-f
- Those with odd Stages and a place notation of n following the leadhead have codes g-m
- Those with even Stages and a place notation of 3n following the leadhead have codes p-q
- Those with even Stages and a place notation of - following the leadhead have codes r-s
Any methods not falling in the above groupings are not given a leadhead code even if they have Plain Bob or Grandsire leadheads.
B.
Plain Bob Leadhead Codes for Even Stages
C.
Plain Bob Leadhead Codes for Odd Stages
D.
Grandsire Leadhead Codes for Odd Stages
E.
Grandsire Leadhead Codes for Even Stages
F.
Alternative Leadhead Code System
As an alternative to the letter codes shown above, Methods with Plain Bob Leadheads can be coded according to the number of Plain Leads of Plain Bob that it takes to reach the same Leadhead as it does with one Plain Lead of the Method in question.
Example 1: The first Leadhead of Cambridge Surprise Major is 15738264. This same Leadhead would be reached by ringing two Plain Leads of Plain Bob Major. Cambridge Surprise Major is therefore referred to as a "+2" Method.
Example 2: The first Leadhead of London Surprise Minor is 142635.
This same Leadhead would be reached by ringing four Plain Leads of Plain Bob Minor.
Going forward for four Plain Leads of Plain Bob Minor reaches the same Leadhead as going
backwards for one Plain Lead,
so London Surprise Minor is referred to as a "-1" method.
Pluses are used up to and including the halfway point of a Plain Course
of Plain Bob, and minuses are used after the halfway point of the Plain Course.
So in Minor, the codes would range from -2 to +2,
in Triples the codes would range from -2 to +3,
in Major the codes would range from -3 to +3, and so on.
For Plain Bob Leadhead Methods where nth's Place rather than 2nd's Place is made at the Leadend Change (where n is the Stage), the letter 'n' is added to the code.
Example 3: The first Leadhead of Bristol Surprise Major is 14263857 and Bristol S Major is an 8th's Place Leadend Method. Bristol S Major is therefore referred to as a "-1n" Method.
Methods that have one Plain Lead in their Plain Course are referred to as "+0" Methods.
Note that this alternative Leadhead code system is usually only used for Plain Bob Leadhead Methods with even Stages, and not for Plain Bob Leadhead Methods with odd Stages, nor for Grandsire Leadhead Methods.