NOTATIO

I'm reading along with the music as I listen to Messiaen's "L'Ascension".

I'm noting lots of strange notation quirks.

For example, he seems to always use upside down "Down bow" markings, even when they're above the staff, no divisi, nothing. I'm not seeing any particular reason for this. All the "Up bow" markings are as one would expect them. This only seems to apply to his "Down bows".

Another one, which I find makes the score harder to read, is that all tied notes, the ties only seem to attach from the "tied to" note, like a short backward "L.V." marking. That seems a rather major change from standard practice, isn't it?

The ‘tied to’ notation you mention was quite common for a while, especially but not only in French music. I've just checked, and it can be found in Boulez. I used it for a period in my own manuscripts, as it seemed to reduce clutter, but I later abandoned it. No performer ever commented either directly or via comments pencilled in the parts (which could be quite outspoken - about conductors, singers, producers, my spelling[!] et al, but never ties).

FWIW someone on Twitter has linked to the score of Boulez’s Éclat - Multiples & it seems to have normal ties, not the short backwards ties in the rather old printed Boulez scores I have here. https://www.youtube.com/watch?v=7ggRDq8SWnw

hmmm.
oh well.
I personally found it a bit confusing.
the other way around might have made more sense, but then it would have been confused with actual laisser-vibrer.