diff --git a/output/schema/schema.json b/output/schema/schema.json
index 6e828f28c6..6e72a59af6 100644
--- a/output/schema/schema.json
+++ b/output/schema/schema.json
@@ -39960,7 +39960,7 @@
         "name": "AggregateName",
         "namespace": "_types"
       },
-      "specLocation": "_types/common.ts#L139-L143",
+      "specLocation": "_types/common.ts#L141-L145",
       "type": {
         "kind": "instance_of",
         "type": {
@@ -40169,7 +40169,7 @@
         "name": "ByteSize",
         "namespace": "_types"
       },
-      "specLocation": "_types/common.ts#L90-L91",
+      "specLocation": "_types/common.ts#L92-L93",
       "type": {
         "items": [
           {
@@ -40222,7 +40222,7 @@
         "name": "Bytes",
         "namespace": "_types"
       },
-      "specLocation": "_types/common.ts#L163-L181"
+      "specLocation": "_types/common.ts#L165-L183"
     },
     {
       "kind": "type_alias",
@@ -40365,7 +40365,7 @@
         "name": "ClusterInfoTarget",
         "namespace": "_types"
       },
-      "specLocation": "_types/common.ts#L378-L384"
+      "specLocation": "_types/common.ts#L380-L386"
     },
     {
       "kind": "type_alias",
@@ -40373,7 +40373,7 @@
         "name": "ClusterInfoTargets",
         "namespace": "_types"
       },
-      "specLocation": "_types/common.ts#L386-L386",
+      "specLocation": "_types/common.ts#L388-L388",
       "type": {
         "items": [
           {
@@ -40592,7 +40592,7 @@
         "name": "Conflicts",
         "namespace": "_types"
       },
-      "specLocation": "_types/common.ts#L183-L192"
+      "specLocation": "_types/common.ts#L185-L194"
     },
     {
       "kind": "interface",
@@ -40725,7 +40725,7 @@
         "name": "DataStreamName",
         "namespace": "_types"
       },
-      "specLocation": "_types/common.ts#L85-L86",
+      "specLocation": "_types/common.ts#L87-L88",
       "type": {
         "kind": "instance_of",
         "type": {
@@ -40740,7 +40740,7 @@
         "name": "DataStreamNames",
         "namespace": "_types"
       },
-      "specLocation": "_types/common.ts#L88-L88",
+      "specLocation": "_types/common.ts#L90-L90",
       "type": {
         "items": [
           {
@@ -41113,7 +41113,7 @@
         "namespace": "_types"
       },
       "properties": [],
-      "specLocation": "_types/common.ts#L154-L155"
+      "specLocation": "_types/common.ts#L156-L157"
     },
     {
       "generics": [
@@ -41306,7 +41306,7 @@
         "name": "ExpandWildcard",
         "namespace": "_types"
       },
-      "specLocation": "_types/common.ts#L201-L215"
+      "specLocation": "_types/common.ts#L203-L217"
     },
     {
       "kind": "type_alias",
@@ -41314,7 +41314,7 @@
         "name": "ExpandWildcards",
         "namespace": "_types"
       },
-      "specLocation": "_types/common.ts#L217-L217",
+      "specLocation": "_types/common.ts#L219-L219",
       "type": {
         "items": [
           {
@@ -41345,7 +41345,7 @@
         "name": "Field",
         "namespace": "_types"
       },
-      "specLocation": "_types/common.ts#L132-L133",
+      "specLocation": "_types/common.ts#L134-L135",
       "type": {
         "kind": "instance_of",
         "type": {
@@ -41659,7 +41659,7 @@
         "name": "Fields",
         "namespace": "_types"
       },
-      "specLocation": "_types/common.ts#L134-L134",
+      "specLocation": "_types/common.ts#L136-L136",
       "type": {
         "items": [
           {
@@ -41754,7 +41754,7 @@
         "name": "Fuzziness",
         "namespace": "_types"
       },
-      "specLocation": "_types/common.ts#L127-L128",
+      "specLocation": "_types/common.ts#L129-L130",
       "type": {
         "items": [
           {
@@ -42369,7 +42369,7 @@
         "name": "HealthStatus",
         "namespace": "_types"
       },
-      "specLocation": "_types/common.ts#L219-L239"
+      "specLocation": "_types/common.ts#L221-L241"
     },
     {
       "kind": "type_alias",
@@ -42392,7 +42392,7 @@
         "name": "HttpHeaders",
         "namespace": "_types"
       },
-      "specLocation": "_types/common.ts#L152-L152",
+      "specLocation": "_types/common.ts#L154-L154",
       "type": {
         "key": {
           "kind": "instance_of",
@@ -42869,7 +42869,7 @@
           }
         }
       ],
-      "specLocation": "_types/common.ts#L332-L359"
+      "specLocation": "_types/common.ts#L334-L361"
     },
     {
       "inherits": {
@@ -43008,7 +43008,7 @@
           }
         }
       ],
-      "specLocation": "_types/common.ts#L321-L330"
+      "specLocation": "_types/common.ts#L323-L332"
     },
     {
       "inherits": {
@@ -43261,7 +43261,7 @@
         "name": "Level",
         "namespace": "_types"
       },
-      "specLocation": "_types/common.ts#L249-L253"
+      "specLocation": "_types/common.ts#L251-L255"
     },
     {
       "kind": "enum",
@@ -43282,6 +43282,31 @@
       },
       "specLocation": "_types/Lifecycle.ts#L20-L24"
     },
+    {
+      "kind": "type_alias",
+      "name": {
+        "name": "ManagedBy",
+        "namespace": "_types"
+      },
+      "specLocation": "_types/common.ts#L74-L74",
+      "type": {
+        "items": [
+          {
+            "kind": "literal_value",
+            "value": "Index Lifecycle Management"
+          },
+          {
+            "kind": "literal_value",
+            "value": "Data Stream Lifecycle"
+          },
+          {
+            "kind": "literal_value",
+            "value": "Unmanaged"
+          }
+        ],
+        "kind": "union_of"
+      }
+    },
     {
       "kind": "type_alias",
       "name": {
@@ -43516,7 +43541,7 @@
         "name": "Metadata",
         "namespace": "_types"
       },
-      "specLocation": "_types/common.ts#L93-L93",
+      "specLocation": "_types/common.ts#L95-L95",
       "type": {
         "key": {
           "kind": "instance_of",
@@ -43571,7 +43596,7 @@
         "name": "MinimumShouldMatch",
         "namespace": "_types"
       },
-      "specLocation": "_types/common.ts#L157-L161",
+      "specLocation": "_types/common.ts#L159-L163",
       "type": {
         "items": [
           {
@@ -43600,7 +43625,7 @@
         "name": "MultiTermQueryRewrite",
         "namespace": "_types"
       },
-      "specLocation": "_types/common.ts#L129-L130",
+      "specLocation": "_types/common.ts#L131-L132",
       "type": {
         "kind": "instance_of",
         "type": {
@@ -43615,7 +43640,7 @@
         "name": "Name",
         "namespace": "_types"
       },
-      "specLocation": "_types/common.ts#L74-L74",
+      "specLocation": "_types/common.ts#L76-L76",
       "type": {
         "kind": "instance_of",
         "type": {
@@ -43630,7 +43655,7 @@
         "name": "Names",
         "namespace": "_types"
       },
-      "specLocation": "_types/common.ts#L75-L75",
+      "specLocation": "_types/common.ts#L77-L77",
       "type": {
         "items": [
           {
@@ -43660,7 +43685,7 @@
         "name": "Namespace",
         "namespace": "_types"
       },
-      "specLocation": "_types/common.ts#L77-L77",
+      "specLocation": "_types/common.ts#L79-L79",
       "type": {
         "kind": "instance_of",
         "type": {
@@ -43886,7 +43911,7 @@
         "name": "NodeName",
         "namespace": "_types"
       },
-      "specLocation": "_types/common.ts#L82-L83",
+      "specLocation": "_types/common.ts#L84-L85",
       "type": {
         "kind": "instance_of",
         "type": {
@@ -44222,7 +44247,7 @@
         "name": "OpType",
         "namespace": "_types"
       },
-      "specLocation": "_types/common.ts#L255-L264"
+      "specLocation": "_types/common.ts#L257-L266"
     },
     {
       "kind": "type_alias",
@@ -44230,7 +44255,7 @@
         "name": "Password",
         "namespace": "_types"
       },
-      "specLocation": "_types/common.ts#L195-L195",
+      "specLocation": "_types/common.ts#L197-L197",
       "type": {
         "kind": "instance_of",
         "type": {
@@ -44272,7 +44297,7 @@
         "name": "PipelineName",
         "namespace": "_types"
       },
-      "specLocation": "_types/common.ts#L80-L80",
+      "specLocation": "_types/common.ts#L82-L82",
       "type": {
         "kind": "instance_of",
         "type": {
@@ -44399,7 +44424,7 @@
         "name": "PropertyName",
         "namespace": "_types"
       },
-      "specLocation": "_types/common.ts#L124-L124",
+      "specLocation": "_types/common.ts#L126-L126",
       "type": {
         "kind": "instance_of",
         "type": {
@@ -44671,7 +44696,7 @@
         "name": "Refresh",
         "namespace": "_types"
       },
-      "specLocation": "_types/common.ts#L266-L273"
+      "specLocation": "_types/common.ts#L268-L275"
     },
     {
       "kind": "interface",
@@ -44773,7 +44798,7 @@
         "name": "RelationName",
         "namespace": "_types"
       },
-      "specLocation": "_types/common.ts#L125-L125",
+      "specLocation": "_types/common.ts#L127-L127",
       "type": {
         "kind": "instance_of",
         "type": {
@@ -45635,7 +45660,7 @@
         "name": "SearchType",
         "namespace": "_types"
       },
-      "specLocation": "_types/common.ts#L275-L280"
+      "specLocation": "_types/common.ts#L277-L282"
     },
     {
       "kind": "interface",
@@ -45950,7 +45975,7 @@
         "name": "SequenceNumber",
         "namespace": "_types"
       },
-      "specLocation": "_types/common.ts#L122-L122",
+      "specLocation": "_types/common.ts#L124-L124",
       "type": {
         "kind": "instance_of",
         "type": {
@@ -45965,7 +45990,7 @@
         "name": "Service",
         "namespace": "_types"
       },
-      "specLocation": "_types/common.ts#L78-L78",
+      "specLocation": "_types/common.ts#L80-L80",
       "type": {
         "kind": "instance_of",
         "type": {
@@ -46184,7 +46209,7 @@
         "name": "Slices",
         "namespace": "_types"
       },
-      "specLocation": "_types/common.ts#L361-L366",
+      "specLocation": "_types/common.ts#L363-L368",
       "type": {
         "items": [
           {
@@ -46217,7 +46242,7 @@
         "name": "SlicesCalculation",
         "namespace": "_types"
       },
-      "specLocation": "_types/common.ts#L368-L376"
+      "specLocation": "_types/common.ts#L370-L378"
     },
     {
       "kind": "type_alias",
@@ -46613,7 +46638,7 @@
         "name": "SuggestMode",
         "namespace": "_types"
       },
-      "specLocation": "_types/common.ts#L282-L295"
+      "specLocation": "_types/common.ts#L284-L297"
     },
     {
       "description": "The suggestion name as returned from the server. Depending whether typed_keys is specified this could come back\nin the form of `name#type` instead of simply `name`",
@@ -46622,7 +46647,7 @@
         "name": "SuggestionName",
         "namespace": "_types"
       },
-      "specLocation": "_types/common.ts#L145-L149",
+      "specLocation": "_types/common.ts#L147-L151",
       "type": {
         "kind": "instance_of",
         "type": {
@@ -46691,7 +46716,7 @@
         "name": "TaskId",
         "namespace": "_types"
       },
-      "specLocation": "_types/common.ts#L126-L126",
+      "specLocation": "_types/common.ts#L128-L128",
       "type": {
         "items": [
           {
@@ -46767,7 +46792,7 @@
         "name": "ThreadType",
         "namespace": "_types"
       },
-      "specLocation": "_types/common.ts#L297-L303"
+      "specLocation": "_types/common.ts#L299-L305"
     },
     {
       "description": "Time of day, expressed as HH:MM:SS",
@@ -47123,7 +47148,7 @@
         "name": "Username",
         "namespace": "_types"
       },
-      "specLocation": "_types/common.ts#L194-L194",
+      "specLocation": "_types/common.ts#L196-L196",
       "type": {
         "kind": "instance_of",
         "type": {
@@ -47138,7 +47163,7 @@
         "name": "Uuid",
         "namespace": "_types"
       },
-      "specLocation": "_types/common.ts#L119-L119",
+      "specLocation": "_types/common.ts#L121-L121",
       "type": {
         "kind": "instance_of",
         "type": {
@@ -47153,7 +47178,7 @@
         "name": "VersionNumber",
         "namespace": "_types"
       },
-      "specLocation": "_types/common.ts#L96-L96",
+      "specLocation": "_types/common.ts#L98-L98",
       "type": {
         "kind": "instance_of",
         "type": {
@@ -47168,7 +47193,7 @@
         "name": "VersionString",
         "namespace": "_types"
       },
-      "specLocation": "_types/common.ts#L98-L98",
+      "specLocation": "_types/common.ts#L100-L100",
       "type": {
         "kind": "instance_of",
         "type": {
@@ -47200,7 +47225,7 @@
         "name": "VersionType",
         "namespace": "_types"
       },
-      "specLocation": "_types/common.ts#L100-L116"
+      "specLocation": "_types/common.ts#L102-L118"
     },
     {
       "kind": "enum",
@@ -47216,7 +47241,7 @@
         "name": "WaitForActiveShardOptions",
         "namespace": "_types"
       },
-      "specLocation": "_types/common.ts#L305-L309"
+      "specLocation": "_types/common.ts#L307-L311"
     },
     {
       "codegenNames": [
@@ -47228,7 +47253,7 @@
         "name": "WaitForActiveShards",
         "namespace": "_types"
       },
-      "specLocation": "_types/common.ts#L136-L137",
+      "specLocation": "_types/common.ts#L138-L139",
       "type": {
         "items": [
           {
@@ -47275,7 +47300,7 @@
         "name": "WaitForEvents",
         "namespace": "_types"
       },
-      "specLocation": "_types/common.ts#L311-L318"
+      "specLocation": "_types/common.ts#L313-L320"
     },
     {
       "kind": "interface",
@@ -110086,8 +110111,8 @@
           "type": {
             "kind": "instance_of",
             "type": {
-              "name": "string",
-              "namespace": "_builtins"
+              "name": "ManagedBy",
+              "namespace": "_types"
             }
           }
         },
@@ -110221,7 +110246,7 @@
           }
         }
       ],
-      "specLocation": "indices/_types/DataStream.ts#L32-L104"
+      "specLocation": "indices/_types/DataStream.ts#L33-L105"
     },
     {
       "kind": "interface",
@@ -110273,8 +110298,8 @@
           "type": {
             "kind": "instance_of",
             "type": {
-              "name": "string",
-              "namespace": "_builtins"
+              "name": "ManagedBy",
+              "namespace": "_types"
             }
           }
         },
@@ -110291,7 +110316,7 @@
           }
         }
       ],
-      "specLocation": "indices/_types/DataStream.ts#L113-L134"
+      "specLocation": "indices/_types/DataStream.ts#L114-L135"
     },
     {
       "description": "Data lifecycle denotes that a data stream is managed by the data stream lifecycle and contains the configuration.",
@@ -110538,7 +110563,7 @@
           }
         }
       ],
-      "specLocation": "indices/_types/DataStream.ts#L106-L111"
+      "specLocation": "indices/_types/DataStream.ts#L107-L112"
     },
     {
       "kind": "interface",
@@ -110559,7 +110584,7 @@
           }
         }
       ],
-      "specLocation": "indices/_types/DataStream.ts#L136-L138"
+      "specLocation": "indices/_types/DataStream.ts#L137-L139"
     },
     {
       "kind": "interface",
diff --git a/output/typescript/types.ts b/output/typescript/types.ts
index f01534ec88..1b03bc60b0 100644
--- a/output/typescript/types.ts
+++ b/output/typescript/types.ts
@@ -2354,6 +2354,8 @@ export type Level = 'cluster' | 'indices' | 'shards'
 
 export type LifecycleOperationMode = 'RUNNING' | 'STOPPING' | 'STOPPED'
 
+export type ManagedBy = 'Index Lifecycle Management' | 'Data Stream Lifecycle' | 'Unmanaged'
+
 export type MapboxVectorTiles = ArrayBuffer
 
 export interface MergesStats {
@@ -9658,7 +9660,7 @@ export interface IndicesDataStream {
   generation: integer
   hidden: boolean
   ilm_policy?: Name
-  next_generation_managed_by: string
+  next_generation_managed_by: ManagedBy
   prefer_ilm: boolean
   indices: IndicesDataStreamIndex[]
   lifecycle?: IndicesDataStreamLifecycleWithRollover
@@ -9674,7 +9676,7 @@ export interface IndicesDataStreamIndex {
   index_name: IndexName
   index_uuid: Uuid
   ilm_policy?: Name
-  managed_by: string
+  managed_by: ManagedBy
   prefer_ilm: boolean
 }
 
diff --git a/specification/_types/common.ts b/specification/_types/common.ts
index 37f3b616ad..58b1e365de 100644
--- a/specification/_types/common.ts
+++ b/specification/_types/common.ts
@@ -71,6 +71,8 @@ export type Metrics = string | string[]
 
 export type ClusterAlias = string
 
+export type ManagedBy = 'Index Lifecycle Management' | 'Data Stream Lifecycle' | 'Unmanaged'
+
 export type Name = string
 export type Names = Name | Name[]
 
diff --git a/specification/indices/_types/DataStream.ts b/specification/indices/_types/DataStream.ts
index 031e7dbdb6..b508bc5aa0 100644
--- a/specification/indices/_types/DataStream.ts
+++ b/specification/indices/_types/DataStream.ts
@@ -22,6 +22,7 @@ import {
   Field,
   HealthStatus,
   IndexName,
+  ManagedBy,
   Metadata,
   Name,
   Uuid
@@ -57,7 +58,7 @@ export class DataStream {
   /**
    * Name of the lifecycle system that'll manage the next generation of the data stream.
    */
-  next_generation_managed_by: string
+  next_generation_managed_by: ManagedBy
   /**
    * Indicates if ILM should take precedence over DSL in case both are configured to managed this data stream.
    */
@@ -126,7 +127,7 @@ export class DataStreamIndex {
   /**
    * Name of the lifecycle system that's currently managing this backing index.
    */
-  managed_by: string
+  managed_by: ManagedBy
   /**
    * Indicates if ILM should take precedence over DSL in case both are configured to manage this index.
    */