diff --git a/database/db_types.anubis b/database/db_types.anubis
index 0b63b21..e99d9f8 100644
--- a/database/db_types.anubis
+++ b/database/db_types.anubis
@@ -5,6 +5,7 @@
  * Time: 22:41
  * 
  */
+transmit system/convert.anubis
 transmit tools/basis.anubis
 transmit tools/ISO-8601.anubis
 
@@ -35,6 +36,17 @@ public define String
     db_id(_idx) then abs_to_decimal(_idx)
   }.
 
+public define Maybe(Int)
+  to_mb_Int
+  (
+    DB_id idx
+  )=
+  if idx is
+  {
+    none        then failure,
+    db_id(_idx) then success(_idx)
+  }.
+  
 public define JsonValue
   to_JsonValue
   (
@@ -90,6 +102,32 @@ public define DB_id
     db_id(value)
 .
 
+public define Maybe(DB_id)
+  to_mb_DB_id
+  (
+    String  db_id_str
+  )=
+  if decimal_scan(db_id_str) is
+  {
+    failure             then failure,
+    success(db_id_int)  then  success(to_DB_id(db_id_int))
+  }
+.
+
+public define Maybe(DB_id)
+  to_mb_DB_id
+  (
+    Maybe(String)  mb_db_id_str
+  )=
+  if mb_db_id_str is
+  {
+    failure             then failure,
+    success(db_id_str)  then to_mb_DB_id(db_id_str)
+  }
+.
+
+
+
 /**
  * produce path from db_id to optimize fs access and never have more than 100 folders
  */
--
libgit2 0.21.4