diff --git a/object/types.proto b/object/types.proto
index 0a5c688..a6505c0 100644
--- a/object/types.proto
+++ b/object/types.proto
@@ -9,9 +9,9 @@ import "storagegroup/types.proto";
 
 // Header groups the information about the NeoFS object.
 message Header {
-    // System groups mandatory information about the object.
+    // Main groups mandatory information about the object.
     // Message fields are presented in all NeoFS objects.
-    message System {
+    message Main {
         // PayloadLength carries length of the object payload.
         // Each object has a fixed payload length since it's immutable.
         uint64 PayloadLength = 1;
@@ -21,9 +21,9 @@ message Header {
         // OwnerID carries identifier the object owner in a binary format.
         bytes OwnerID = 3;
     }
-    // System carries the main part of the header.
-    // System MUST NOT be NULL.
-    System system = 1;
+    // Main carries the main part of the header.
+    // Main MUST NOT be NULL.
+    Main main = 1;
 
     // Extended groups additional information about the object.
     // It encapsulates both user and system attributes needed to regulate
diff --git a/proto-docs/object.md b/proto-docs/object.md
index 864d852..9dc303a 100644
--- a/proto-docs/object.md
+++ b/proto-docs/object.md
@@ -35,7 +35,7 @@
     - [Header.Extended.Integrity](#object.Header.Extended.Integrity)
     - [Header.Extended.Split](#object.Header.Extended.Split)
     - [Header.Extended.Tombstone](#object.Header.Extended.Tombstone)
-    - [Header.System](#object.Header.System)
+    - [Header.Main](#object.Header.Main)
     - [Object](#object.Object)
     
 
@@ -367,7 +367,7 @@ Header groups the information about the NeoFS object.
 
 | Field | Type | Label | Description |
 | ----- | ---- | ----- | ----------- |
-| system | [Header.System](#object.Header.System) |  | System carries the main part of the header. System MUST NOT be NULL. |
+| main | [Header.Main](#object.Header.Main) |  | Main carries the main part of the header. Main MUST NOT be NULL. |
 | extended | [Header.Extended](#object.Header.Extended) |  | Extended carries the additional part of the header. |
 
 
@@ -439,10 +439,10 @@ Tombstone groups the options for deleting an object.
 
 
 
-<a name="object.Header.System"></a>
+<a name="object.Header.Main"></a>
 
-### Message Header.System
-System groups mandatory information about the object.
+### Message Header.Main
+Main groups mandatory information about the object.
 Message fields are presented in all NeoFS objects.