file/data: update posix file systems/links

lectures/file-and-data-systems/slides.qmd

@@ -109,6 +109,7 @@ from "Small Gods" by Terry Pratchett
 * Usual means are (symbolic) names or (numerical) identifiers
 * Must be determined at time of data storage
 * Either implicit, stored with the data or externally
+* Medium is "formatted" to provide required infrastructure 
 
 ## The more the merrier
 
@@ -117,9 +118,9 @@ from "Small Gods" by Terry Pratchett
     * Support optimized data storage or access
   * Defined by users or applications
     * Allows indexing of data beyond name or id
-    * Especially for _Content-Adressed Storage_[^1] [(git2 lecture)](/lecture-materials/lectures/git2/slides.html#content-addressable-store)
+    * Especially for _Content-Adressed Storage_[^1] [(git2)](/lecture-materials/lectures/git2/slides.html#content-addressable-store)
 
-[^1]: not to be confused with _Content-Adressable Memory_
+[^1]: not the same as _Content-Adressable Memory_ [(data structures)](/lecture-materials/lectures/data-structures/slides.html#dictionaries)
 
 ## File systems (POSIX)
 
@@ -135,11 +136,13 @@ from "Small Gods" by Terry Pratchett
   * times of state change, permissions
   * contains actual block locations
 
-## Directories
+## Directories and Links
 
 * Directories map names to inode numbers
-  * More than one name possible ("hard links")
-  * inode's life time managed by "link count"
+* More than one name possible ("hard links")
+  * More than one directory with same name
+  * More than one name in one directory
+* inode's life time managed by "link count"
 
 ## Inodes / blocks / ...