In reply to <a href="https://eclecticlight.co/2026/04/21/the-macl-extended-attribute/comment-page-1/#comment-113204">Marc</a>. Well, you won't find any MACL xattrs from before Catalina, so they haven't been accumulating for long. There is a practical limit you wouldn't want them to exceed. xattr data can be stored with the xattr in file system data so long as they aren't larger than 3,804 bytes. Above that size they're stored as separate data streams. A little arithmetic shows that critical size is around 211 header-UUID pairs, which seems implausible in normal use. As they're only superceded by a restart, assuming the Mac is only started up once daily, that would represent a new header-UUID pair every working day for a year. Howard.