diff --git a/README.md b/README.md
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+++ b/README.md
@@ -29,7 +29,7 @@ sudo cp ${GOPATH}/bin/photocatalog /usr/local/bin/photocatalog
 
 The tool supports the following organization modes:
 
-- **copy** — Copies files to the target directory. If the filesystem supports it, uses Copy-on-Write (COW) for efficiency.
+- **copy** — Copies files to the target directory. If the filesystem supports it, uses Copy-on-Write (COW) for efficiency (via FICLONE ioctl call).
 - **hardlink** — Creates hardlinks to the source files, saving disk space. Ideal if the source and target are on the same partition, though file permissions remain linked to the original.
 - **move** — Moves files from the source to the target directory.
 - **symlink** — Creates symbolic links at the target pointing to the source files.