diff --git a/file-formats/intf/format.md b/file-formats/intf/format.md
index d7a5b50d3..0c683fc25 100644
--- a/file-formats/intf/format.md
+++ b/file-formats/intf/format.md
@@ -9,3 +9,5 @@ File | Content
  --- | ---
 [`zif_aff_example.intf.json`](./examples/zif_aff_example.intf.json)         | Properties and descriptions of the ABAP interface
 [`zif_aff_example.intf.abap`](./examples/zif_aff_example.intf.abap)         | Interface source code
+
+Documentation of interfaces is not covered, yet.
diff --git a/file-formats/intf/intf.json b/file-formats/intf/intf.json
index 8f1a42fad..8b03bdfe1 100644
--- a/file-formats/intf/intf.json
+++ b/file-formats/intf/intf.json
@@ -50,6 +50,28 @@
         "abapLanguageVersion"
       ]
     },
+    "category": {
+      "title": "Interface category",
+      "description": "Interface category",
+      "type": "string",
+      "enum": [
+        "standard",
+        "classicBadi",
+        "dbProcedureProxy",
+        "enterpriseService"
+      ],
+      "enumDescriptions": [
+        "Standard interface",
+        "Interface definition of a classic BAdI",
+        "Generated interface of a database procedure proxy",
+        "Generated interface of enterprise services"
+      ]
+    },
+    "proxy": {
+      "title": "Interface is a proxy interface",
+      "description": "Interface is a proxy interface",
+      "type": "boolean"
+    },
     "types": {
       "type": "array",
       "title": "Type Descriptions",
diff --git a/file-formats/intf/zif_aff_intf_v1.intf.abap b/file-formats/intf/zif_aff_intf_v1.intf.abap
index 782dc5550..1be337c9b 100644
--- a/file-formats/intf/zif_aff_intf_v1.intf.abap
+++ b/file-formats/intf/zif_aff_intf_v1.intf.abap
@@ -1,5 +1,19 @@
 INTERFACE zif_aff_intf_v1 PUBLIC.
 
+  TYPES:
+    category_base TYPE n LENGTH 2,
+    "! Interface category
+    BEGIN OF ENUM category BASE TYPE category_base,
+      "! Standard interface
+      standard           VALUE IS INITIAL,
+      "! Interface definition of a classic BAdI
+      classic_badi       VALUE '01',
+      "! Generated interface of a database procedure proxy
+      db_procedure_proxy VALUE '65',
+      "! Generated interface of enterprise services
+      enterprise_service VALUE '90',
+    END OF ENUM category.
+
   TYPES:
     "! Component description (e.g., for methods, attributes, types)
     BEGIN OF component_description,
@@ -20,9 +34,9 @@ INTERFACE zif_aff_intf_v1 PUBLIC.
       "! Description of the component
       description TYPE zif_aff_types_v1=>description_60,
       "! Parameter descriptions
-      parameters TYPE subcomponent_descriptions,
+      parameters  TYPE subcomponent_descriptions,
       "! Exception descriptions
-      exceptions TYPE subcomponent_descriptions,
+      exceptions  TYPE subcomponent_descriptions,
     END OF method,
     "! Method descriptions
     methods TYPE SORTED TABLE OF method WITH UNIQUE KEY name.
@@ -35,7 +49,7 @@ INTERFACE zif_aff_intf_v1 PUBLIC.
       "! Description of the component
       description TYPE zif_aff_types_v1=>description_60,
       "! Parameter descriptions
-      parameters TYPE subcomponent_descriptions,
+      parameters  TYPE subcomponent_descriptions,
     END OF event,
     "! Event descriptions
     events TYPE SORTED TABLE OF event WITH UNIQUE KEY name.
@@ -43,7 +57,11 @@ INTERFACE zif_aff_intf_v1 PUBLIC.
   TYPES:
     "! Interface properties
     BEGIN OF main,
-      header TYPE zif_aff_types_v1=>head-header,
+      header     TYPE zif_aff_types_v1=>header,
+      "! Interface category
+      category   TYPE category,
+      "! Interface is a proxy interface
+      proxy      TYPE abap_bool,
       "! Type descriptions
       types      TYPE component_descriptions,
       "! Attribute descriptions
diff --git a/file-formats/intf/zif_aff_types_v1.intf.abap b/file-formats/intf/zif_aff_types_v1.intf.abap
index 8450a7f1d..b35860903 100644
--- a/file-formats/intf/zif_aff_types_v1.intf.abap
+++ b/file-formats/intf/zif_aff_types_v1.intf.abap
@@ -13,20 +13,15 @@ INTERFACE zif_aff_types_v1 PUBLIC.
     END OF ENUM abap_language_version.
 
   TYPES:
-    "! Head to be included in each object type
-    BEGIN OF head,
-      "! Location of the corresponding JSON schema
-      schema TYPE string,
-      "! The header for an ABAP main object
-      BEGIN OF header,
-        "! Description of the ABAP object
-        description        TYPE string,
-        "! Original language of the ABAP object
-        master_language    TYPE language,
-        "! ABAP language version
-        abap_langu_version TYPE abap_language_version,
-      END OF header,
-    END OF head.
+    "! The header for an ABAP main object
+    BEGIN OF header,
+      "! Description of the ABAP object
+      description        TYPE string,
+      "! Original language of the ABAP object
+      master_language    TYPE language,
+      "! ABAP language version
+      abap_langu_version TYPE abap_language_version,
+    END OF header.
 
   "! Description with 60 characters
   TYPES description_60 TYPE c LENGTH 60.
@@ -34,4 +29,4 @@ INTERFACE zif_aff_types_v1 PUBLIC.
   "! Object name with max. length 30
   TYPES object_name_30 TYPE c LENGTH 30.
 
-ENDINTERFACE.
\ No newline at end of file
+ENDINTERFACE.