Then, 'extra' does not mean the same thing for you and me
I explain why in my complete text (part beginning with "Actually"):
"you transform the normal registers from blocks 1 to 3 in 'extra' registers when they are converted into a file by both emulators. Actually, it's the same registers but with a different number, because the emulators don't generate 4 files, one for each block, but only 1 file."
The first column is for blocks.
The second is for real RTC (and emulated RTC of course). Where do you see I transformed registers here?
The third is for the registers "with different numbers" on OpenMSX.
The fourth is for the registers "with different numbers" on BlueMSX".
Explain where the problem is! I just want to understand. Removing this doesn't solve the problem.
I have explained, but you give another meaning to the word 'extra', just because there are not 4 files, one for each block. The only extra data are in the blueMSX file.
'Extra' for me = 'does not have a corresponding RTC register".
I prefer to have this section removed than having a text confusing two kinds of 'extra' things, according your criteria.
You should at least precede the table with a text explaining that the emulators don't generate 4 files, one for each block, but only 1 file, what provokes the renumeration of the registers from blocks 1 to 3.
I suggest also to put after the table all the explanations about the blueMSX 'exotic' registers.
Kana key mapping is switchable on all Japanese MSXs using POKE &HFCAD,n. If n=0 it's set to 50on (CF-3000 here) while if n=1 to 255 it's set to JIS (HB-F1XD, HB-F1XDmk2, HB-F1XDJ, HB-F1XV/Panasonic MSX2+ (except FS-A1FX) and MSX Turbo R here). Former might be intuitive when using a keyboard without kana printed on it because you can alphabetically guess 1 = a, 2 = i, 3 = u and so on. Latter is very useful when typing with modern Japanese physical keyboard which is almost universally JIS.
Where can I place this information? The concepts are like 50on = ABCDEF and JIS = QWERTY. Note modern touch keyboards usually can be arranged to 50on.
I think it can be added as note on the page you mention (after the info about row 11 and before all the matrices), but maybe gdx will have another idea.
A question: does this poke work also on the National FS-4500, FS-4600F, FS-4700, FS-5000F2, FS-5500F1 and FS-5500F2, which have hardware switches to change the kana key mapping?
