Thanks for your invaluable input Bob. There are a number of possibilities where it might make sense to have separate certs, but, like Pete has noted, the issue really does not come up all that often - so maybe we're spinning our wheels. But the question intrigues me from an academic perspective.
Here's the thread that I was referencing:
https://measure.infopop.cc/eve/...=228308924#228308924See Gene Newman's post, at bottom of thread, of 12 August 2010. Gene shares concerns raised by Ron Fitzpatrick and Jane Parks regarding dropping the separate cert for the splits.
Now, here's what I was thinking of regarding the potential value of separate certs for certified splits: I had the great pleasure of joining Bernie Conway's measure team for this year's Hamilton Run For Hope Marathon in Canada - it was a great learning experience for me! And, although Bernie was unfazed I was very impressed by the complexity of this measure!
Here's the main challenge we faced: Mid-marathon, the new 2016 route utilized an arbitrary significant length of parkway which had also been used in the 2008 certified marathon. Although the police let the race use that section again this year, they would not permit us to measure on the parkway this year.
The old course and new course were not the same. To determine the distance of the parkway section we had to locate an old un-certified split, then ride back one kilometer from it to join the new course route and subtract to estimate the length of the verboten section of the route. ( I shared with Bernie that I thought the process was sound but I did not believe I could certify this course in the USA with this procedure - oops, I don't think he liked that ).
In 20/20 hindsight, I surmised that it would have been awesome if we had foreseen this predicament in 2008 and certified the entire parkway split to points outside the Parkway so that we could construct a new course including the old measured parkway component. This procedure would be beyond reproach. (Embedded question: should the new composite course have a lifetime limited to the remaining life of the original 2008 measure?)
So, my thinking is that, in this example, it would be better to be able to reference the parkway segment via its own cert rather than have to discuss the old marathon in a completely new marathon measure. What if the old marathon course had been invalidated? Are its intermediate splits still valid? I feel it would be much cleaner if the splits used to construct my new course stood on their own merit and had their own cert(s) to prove it.
JJ