diff --git a/src/caosadvancedtools/table_json_conversion/table_generator.py b/src/caosadvancedtools/table_json_conversion/table_generator.py
index 1e8f939266eee25a5326f8498fb909e72dfa3ee4..f0e8f6c6d816e4d0ea76e7d776d351e4a5d8ecb5 100644
--- a/src/caosadvancedtools/table_json_conversion/table_generator.py
+++ b/src/caosadvancedtools/table_json_conversion/table_generator.py
@@ -38,6 +38,7 @@ class ColumnType(Enum):
     SCALAR = 1
     LIST = 2
     FOREIGN = 3
+    IGNORE = 3
 
 
 class RowType(Enum):
@@ -62,20 +63,20 @@ class TableTemplateGenerator(ABC):
                       elements of the path within the JSON where the key is needed. Suppose we want
                       to distinguis Persons that are referenced by Trainings, foreign_keys must at
                       least contain the following: {"Training": {"Person": [key1, key2]}}.
-                      Values wihtin the dicts can be a list representing the keys, a tuple where
-                      the first element is the list representing the keys and the second elment is
-                      a dict that allows to set further foreign keys at lower depth. The third
-                      possibility is a dict. In that case no foreign keys exist at that level (
-                      e.g. in the above example there is no foreign key for the path ["Training"].
+                      Values wihtin the dicts can be a list representing the keys or
+                      a dict that allows to set further foreign keys at lower depth.
+                      In latter case if foreign keys exist at that level (
+                      e.g. in the above example there might be further levels below "Person".),
+                      then the keys can be set using the special "__this__" key.
+                      Example: {"Training": {"__this__": ["date"], "Person": [key1, key2]}}
+                      Here, "date" is the sole key for Training.
         """
         pass
 
     def _generate_sheets_from_schema(self, schema: dict, foreign_keys: dict = None
-                                     ) -> dict[str, dict[str, tuple[str, list]]]:
+                                     ) -> dict[str, dict[str, list]]:
         """ generates a sheet definition from a given JSON schema
 
-
-
         Parameters
         ----------
         schema: dict