Two metadata editors, and an app to improve your privacy by cleaning metadata and more. Updated for High Sierra and later.
extended attributes
Where to look for file metadata in the Finder, and how you can customise it, in spite of its apparent confusion. And how APFS takes care of extended attributes for you.
Finder Comments are accessible, easy to use, and unreliable because they rely primarily on data stored in a hidden file. Regular Comment extended attributes are more reliable.
New version of this GUI utility for inspecting and editing extended attributes, for High Sierra and later.
How an obscure ACL can prevent a quarantine flag from being attached to an internet download: demonstration and explanation.
How the new tracking extended attribute is attached to apps, how it’s recorded in a security database, and how it’s checked. But for what purpose?
Ventura introduces a new extended attribute com.apple.provenance, used to mark successful clearance of quarantine. It’s protected by SIP too.
ResEdit changed what was in the resource fork. With Mac OS X, Apple moved away from forks to extended attributes, now used for quarantine flags and more.
Provided in Archive Utility and three command tools, its LZFSE compression even supports APFS special files like clones and sparse files.
Quarantine flags first appeared in 2007. This explains how they work, what they do, and the differences between app and document quarantine.
The Eclectic Light Company 