-/** Directly capture an NTFS volume rather than a generic directory. This flag
- * cannot be combined with ::WIMLIB_ADD_FLAG_DEREFERENCE or
- * ::WIMLIB_ADD_FLAG_UNIX_DATA. */
+/** UNIX-like systems only: Directly capture an NTFS volume rather than a
+ * generic directory. This requires that wimlib was compiled with support for
+ * libntfs-3g.
+ *
+ * This flag cannot be combined with ::WIMLIB_ADD_FLAG_DEREFERENCE or
+ * ::WIMLIB_ADD_FLAG_UNIX_DATA.
+ *
+ * Do not use this flag on Windows, where wimlib already supports all
+ * Windows-native filesystems, including NTFS, through the Windows APIs. */