You ask to discuss about the block data.
Does Bitcoin blockchain "know" about BCH splitting off? I don't think so. According to bitcoin's blockchain BCH doesn't exist.
That BIP activation and the split is recorded probably on BCH chain, which doesn't matter in this discussion, since we talk about bitcoin, not altcoins.
So, I may be wrong, since I don't know the things that good, but imho you are also getting into the discussion things that should not be there.
It's all about how one looks at the things.
the bitcoin code and the bips refer to a block number where a split would happen to start the segwit activation process. and guess what magic blockheight BCH started at...
.. ill leave you to answer that when you have a lightbulb moment.
you can also check bitcoins blockchain for the flag day. by looking at the flags in the header and seeing when certain flags reached their needed amount. this is available in bitcoins block data.
for those that dont want to read hard data, i also supplied a nice lil graph that shows the flags in image form, for nice simple viewing..
shame the fable story tellers that can only shout "wrong because troll" cant show same block data or put it into a nice graph for easy reading.. so atleast dont blame me for not trying. but maybe consider the other side hasnt tried, but has cried
note:
by the way when i get something wrong i can admit it.
it has been 4 years. and memory is what memory is.
so i checked if i was right or wrong about the 148+91 bips.. as some have been demanding i retract my statement because their opinion is that 148+91 were not used. so after checking. they indeed were used.
but here is my admission. it was bip91+148 not bip148+91
i simply got them in the wrong order.
91 succeeded at block 477120 (23rd july)
148 succeeded at block 478,484 (aug1st)
which because of the bait switch of demanding pools flag for segwit. near 99% of pools were making new flag blocks, and BCH didnt get its first(old) block that caused the split until 478558(august 1st)
they were not seeing any old flag blocks for 74 blocks
what you also might find relevant and factual. is why would pools fear bip91+148. well they both indicate mandatory rejecting of old blocks. why would they fear this if most users were not using these softwares that incorporated the bips.
because the NYA nodes(
merchants, exchanges) WERE using software that would reject pools old blocks. this software was the UASF.
pools didn't need all users to run new software to activate a fork. all it needed was the commercial services that allow pools to spend rewards with to use software that will reject blocks that dont fit the commercial services designated rules.
other users didnt need to upgrade due to "backward compatibility" of new stuff.
anyway.. to boil the events down..
the blue line in the graph on previous page was bip91(NYA) and the red line was the segwit
to anyone that still does not want to believe that 148 and 91 were used..
may i refer them to some more prominent bitcoiners they might believe
ill refer you to theymos
https://bitcointalksearch.org/topic/august-1-bip148-preparedness-2017191ill refer you to sipa
https://bitcoin.stackexchange.com/a/56994so if you want to debate that 91+148 were never used.. then argue with them first
though it seems theymos has been maybe a slight instigator in some peoples belief that a chain split didnt happen.. even though bch did happen and is active today as proof.
but hey, at least im linking bips, block numbers and references to other notable members that say that bip91+148 were used..
now lets see the ignorant 'it didnt happen' show their proofs that forks didnt happen and bips were not used.. or lets see them shout and scream and cry "wrong because troll"
have a good day. goodluck