JinJin48

SAP Consultant | BTP · S/4HANA · US Global Rollout

June 23, 2026 · 25 min read

SAP MM Class

The Class is the master data object that defines a classification container in SAP’s cross-application Classification System (CA-CL). It groups one or more Characteristics into a reusable structure that can be assigned to materials, batches, vendors, equipment, and other SAP objects to enable structured search, reporting, and variant configuration. In the MM context, Classes are most commonly applied to Material Masters and Batch Masters, forming the foundation of classification-based procurement and quality management strategies. This article covers Class structure, types, organizational scope, and field-level details — the Characteristic master data object is covered separately in MM-A04-02.

Part 1: Class — Core Concepts (All Modules)#

1.1 What Is the Class?#

A Class is a user-defined grouping template that holds a set of Characteristics. Any SAP object type that supports classification can be assigned to one or more Classes, and its characteristic values recorded against those classes. The class does not store values — it stores the schema (which characteristics apply, in which order, with which constraints). The assigned objects store the values.

1.2 Class Types#

The Class Type determines which SAP object type can be assigned to the class and which business processes can consume the classification data. Selecting the wrong class type makes a class invisible to the intended object and cannot be changed after classes of that type have been used in production.

Design principle: Class Type must be locked down in the blueprint phase. Mixing types (e.g., using 001 for batch purposes instead of 023) causes batch determination failures and requires master data rework. For projects involving both material and batch classification, maintain separate classes of Type 001 and 023.

1.3 Organizational Levels and Data Hierarchy#

The Class is the definition record; classified Object instances reference the Class through separate link tables. The Classification System operates at the Client level — class definitions are cross-plant and cross-company-code — but value scope can be wider when the object type is batch-scoped.

Client scope — Class Definition
   │
   ├── Class Header (KLAH)
   │      One row per Class.
   │      Fields: Class number, Class type, status, validity dates.
   │
   └── Class ↔ Characteristic link (KSML) — M:N relationship
          One row per (Class × Characteristic).
          Fields: position (POSNR), required/optional flag, searchable flag.
          Defines which characteristics apply to objects in this class.

Object Assignment scope (per classified object instance)
   │
   ├── Object ↔ Class link (INOB)
   │      One row per (Object × Class).
   │      Created when classifying a material in MM02 (Classification view).
   │
   └── Characteristic Values per Object (AUSP)
          One row per (Object × Characteristic).
          For Material Master: Client scope (one set of values per material).
          For Batch (class type 023): scope extends to Plant —
          different plants can hold different values for the same batch.

Key design decision: Determine the classification hierarchy depth in the blueprint. SAP Classification supports hierarchical classes (superordinate classes containing subordinate classes), but deeply nested hierarchies are difficult to maintain and search. A flat or two-level hierarchy is recommended for most MM implementations.

1.4 Integration with Other Master Data Objects#

The Class does not stand alone. Its value is realized only when Characteristics are assigned to it and the class is in turn assigned to object masters. The downstream consumers of classification data span multiple modules.

Part 2: MM-Specific Field Details#

2.0 Scope of MM Ownership#

Legend: ◎ = Owner / Critical, ○ = Direct involvement

2.1 Class Header (KLAH)#

The Class Header (table KLAH) is the root record of every class in the SAP Classification System. It defines the identity and operational state of the class — the class number, the object type it can classify (class type), its release status, and the date range during which it is valid. MM administrators create and maintain KLAH records via CL01/CL02 and must understand every header field because an incorrect status or class type cannot easily be corrected after production data is attached.

2.2 Characteristic Assignment (KSML)#

The Characteristic Assignment (table KSML) defines which Characteristics belong to a given class and governs how each characteristic behaves within that class context. An MM consultant assigning characteristics to a class controls the sequence in which they appear on the classification screen, whether each is mandatory or optional for the classifying user, and whether the value entered can be used as a search criterion. Getting this configuration right directly affects the quality and completeness of classification data downstream.

2.3 Material Classification (INOB)#

Material Classification is the act of linking a Material Master record to one or more classes and entering the material’s characteristic values for those classes. In SAP, this is done in MM02 via the “Additional Data” tab, which reveals the Classification view. The resulting database record in INOB captures the class assignment, while the characteristic values entered for that assignment are stored in AUSP. MM consultants own this process for material-level classification and must understand both the INOB assignment record and the value-entry mechanics.

2.4 Batch Classification (AUSP)#

Batch Classification stores characteristic values at the batch level, enabling structured batch search and batch determination. While material classification (Section 2.3) assigns a material to a class, batch classification assigns a specific batch of that material to a class of Type 023 and records values like shelf life remaining, test result, or country of origin for that individual batch. These values are stored in AUSP and are plant-specific — the same batch number at different plants can carry different characteristic values, which is essential for multi-plant quality management.

2.5 Class Hierarchy Definition#

SAP Classification supports an optional class hierarchy in which subordinate classes inherit the position within a structured tree. A class hierarchy is defined in CL02 under “Additional Data” → “Superior Class”, creating a parent–child relationship between classes of the same type. When a hierarchy is active, the transaction CL6CN can perform hierarchical searches — a search at the superordinate class level returns objects assigned to any subordinate class in the tree. This feature is optional and most MM implementations choose a flat structure, but it is valuable for large product catalogs where tiered grouping improves search performance and navigation.

2.6 Batch Determination Strategy#

Batch Determination is the process by which SAP automatically proposes a batch for a goods movement, production order, or outbound delivery based on characteristic values stored in the batch class. MM owns the structural foundation — the Batch Class (Type 023) and its characteristics — while the consuming modules (WM, PP, SD) configure the Batch Search Strategy conditions (transaction MBC1) that query those characteristics. An MM consultant must understand both sides of this boundary to troubleshoot determination failures and advise on characteristic design that supports the downstream strategies.

2.7 Variant Configuration (Class 300)#

In Variant Configuration (VC) scenarios, the configurable material (material type KMAT) is linked to a Class 300, and SD/PP VC consultants design the configuration object, characteristics, and BOM explosion logic. MM’s role is narrower but essential: MM consultants set up the component materials that appear in the super-BOM and ensure the KMAT material’s classification view is correctly configured so that characteristic values entered during sales order configuration can drive BOM selection. Without a correctly maintained classification view on the KMAT material, the VC engine cannot resolve which BOM items to include in the order BOM.

2.8 QM Batch Classification#

QM Batch Classification is the intersection of Quality Management and MM’s batch class structure. QM may define certain characteristics within the batch class (Type 023) as quality-relevant — values for these characteristics are captured either automatically from inspection results or manually at the time of the Usage Decision (UD). MM owns the batch class structure and the characteristic definitions; QM governs when and how characteristic values are set during inspection processing. Understanding this boundary is critical for MM consultants deploying classification in industries where inspection results drive batch status and downstream use decisions.

What to Read Next#

L1) Big Picture

L2-A) Master Data

L2-B) Transaction