`[todo] out/zzz_test_todo.res -> not yet implemented`
-The produced result file contains the magic string "NOT YET IMPLEMENTED".
+The produced result file contains a magic string, like `NOT YET IMPLEMENTED`.
Those are considered the same as expected errors (like a fixme)
It is a success.
-Some engines, libraries or program just print this to simplify the management of tests.
+The magic strings are listed in `todo` files in the root and `sav` directories.
+They are used by engines, libraries or program just print this to simplify the management of tests.
+
+Magic strings are used with `grep -f`, so each line is a pattern that is searched within the res files.
### Skipped