Hi, this is a very big wish for which no infrastructure is present in xorriso. The idea of changing data in existing sessions is not yet in the concept of xorriso (except maybe in -truncate_overwritable). As you mentioned, many operations of xorriso would not be adaptable to in-session editing.
I could imagine a simple tool which patches ISO 9660 superblocks of which the session start is given as block address. This block address would be 0 for the default-mountable superblock. The superblocks of the particular sessions are listed by command -toc under "sbsector". E.g.: TOC layout : Idx , sbsector , Size , Volume Id ISO session : 1 , 32 , 1340329s , HOME_Z_2026_01_24_222106 ISO session : 2 , 1340384 , 34330s , HOME_Z_2026_01_31_225237 The address of the Volume Id is (sbsector + 16) * 2048 + 40 The number of bytes at that adress is 32. See ECMA-119 8.4 "Primary Volume Descriptor" for start bytes (plus one) and end bytes (plus one). E.g. the specs say: 41 to 72 Volume Identifier So the byte offset in the PVD is 40 and the size is (72 - 41 + 1) = 32. Have a nice day :) Thomas
