[r-t] Extents in half leads - Double Oxford T.P.

[Mike Ovenden]

Mentioning D.O.T.P. Minor in a recent post reminded me of a couple of
curious features.

(A) the (2nds place) method is true in the plain course, but the 6ths place
version is not.
(B) the plain course (and hence any complete course) cannot appear in an
extent of the method (not even in separate pieces).

Neither of these features is particularly surprising when you consider that
the method has the wrong parity structure for a standard bobs-only extent.

However, they did incline me to question the decision requiring the plain
course to be a true round block.  When it's possible to ring a true 720,
does the plain course matter that much?  (I rather doubt if a plain course
of it has actually been rung; if it has, would anyone care about its truth?
OTOH I don't see the point of a false extent - not that I find it a
meaningful concept.)

Feature (A) will seem familiar enough to anyone who's played around with
principles.  It's more surprising in a hunter, but only because of the
normal assumptions about parity.

Feature (B) obviously applies to Yorkshire Surprise Major (and presumably a
good many other treble dodging major methods) - see recent discussion of
Colin Wyld's 40320.  However, since most people don't want to ring extents
of anything beyond triples, that's a bit irrelevant.  Can anyone enlighten
me with other examples on 7 or fewer bells?

Regards,
Mike

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PS.  Feature (B) ...

The sets L and R (as defined in recent posts) for DOTP Minor are
L: {123456,135246,142536,154326}
R: {124356,132546,145236,153426}

145236 is a lead end (in effect a half-lead head) in the plain course, but
cannot appear with 123456 in an extent because it appears in the set R.

Double Oxford Treble Place Minor
 - 34 - 16.34 - 34.16 - 34 - 56 le 12

   123456 154632 136245 142563 165324
x  214365 516423 312654 415236 613542
34 124356 156432 132645 145263 163524
x  213465 514623 316254 412536 615342
16 231645 541263 361524 421356 651432
34 321654 451236 631542 241365 561423
x  236145 542163 365124 423156 654132
34 326154 452136 635142 243165 564123
16 362514 425316 653412 234615 546213
x  635241 243561 564321 326451 452631
34 365214 423516 654312 236415 542613
x  632541 245361 563421 324651 456231
56 365241 423561 654321 236451 542631
x  632514 245316 563412 324615 456213
34 362541 425361 653421 234651 546231
x  635214 243516 564312 326415 452613
16 653124 234156 546132 362145 425163
34 563142 324165 456123 632154 245136
x  651324 231456 541632 361245 421563
34 561342 321465 451623 631254 241536
16 516432 312645 415263 613524 214356
x  154623 136254 142536 165342 123465
34 514632 316245 412563 615324 213456
x  156423 132654 145236 163542 124365
   ------ ------ ------ ------ ------
12 154632 136245 142563 165324 123456