This is simply a combination of marcato (aka "strong accent") and staccato. The symbols are not usually overlapped like that, but it is not unknown - see the attached image from "Music Engraving Today" by Steven Powell (which I found in a discussion of how to get Dorico to do this).
I haven't tried, but I imagine that a little tweaking of vertical positions of the two symbols could get them to overlap like this. Paul From: Alberto Simões <albertov...@gmail.com> To: lilypond-user <lilypond-user@gnu.org> Sent: 14/01/2023 17:58 Subject: Unknown expression mark Hello, Friends Anyone knows: - what is this expression mark (in terms of the player) - how to mimic this in Lilypond? Thank you! Alberto