4.3 Bill of Materials (BOM) Explosion in Sales Orders

Bill of Materials (BOM) Explosion in Sales Orders

In many commercial environments, enterprises sell complex product bundles, assembled kits, or promotional packages composed of multiple physical items. For example, a personal computer system may consist of a central processing tower, a monitor, a keyboard, and an operating system license; a corporate promotional package may bundle a leather binder, an executive pen, and a printed catalog.

Rather than requiring customer service representatives to enter every sub-component manually, SAP S/4HANA utilizes Sales Bills of Materials (Sales BOMs). A Sales BOM is created in Production / Sales master data via transaction CS01 with BOM Usage '5' (Sales and Distribution). When a sales representative enters the top-level parent material in a sales order, the system automatically explodes the BOM structure, generating sub-line items for each component according to the quantities configured in CS01.

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Commercial Processing Models: Header-Level vs. Component-Level (ERLA vs. LUMF)

The most important design decision for a sales BOM is the level at which it is priced and managed in inventory. SAP provides two standard models, controlled by the item category group of the main material (MVKE-MTPOS, view Sales: sales org. 2). The official course adds that the item category of the main item also defines how far the structure is exploded.

                                  Sales BOM Architecture
                                            |
               +----------------------------+----------------------------+
               v                                                         v
     Item Cat Group: ERLA                                      Item Cat Group: LUMF
  Main item TAQ: priced, delivered,                        Main item TAP: not priced,
  goods issue on the main item                             no inventory management
  Components TAE: information only                         Components TAN: priced, delivered

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Model 1: Processing at Main Item Level (Item Category Group ERLA)

In the ERLA model, the product is sold, priced, stocked, and shipped as one unit, for example a pre-assembled kit kept in stock under its own material number. The components are listed in the order for information (for example, to print them on the delivery note), but they are not priced and no goods movement is posted for them.

Customizing and Determination Mechanics:

1. Material Master: The main material has item category group ERLA. The components carry NORM.
2. Main Item Determination (VOV4): $\text{Order: OR} + \text{Item Cat Group: ERLA} + \text{Usage: [blank]} + \text{Higher Item: [blank]} \longrightarrow \mathbf{TAQ}$
3. Component Determination (VOV4): $\text{Order: OR} + \text{Item Cat Group: NORM} + \text{Usage: [blank]} + \text{Higher Item: TAQ} \longrightarrow \mathbf{TAE}$

Operational Behavior of TAQ and TAE in VOV7:

• Main Item Category TAQ:
  • Pricing (PRSFD) = 'X': Prices, discounts, and surcharges are determined for the main item only. The customer pays, for example, $1,200 for the complete kit.
  • Schedule lines allowed: The main item has schedule lines (category CP), so availability is checked and goods issue (movement type 601) is posted for the main material.
  • Billing Relevance (FKREL) = 'A': The main item is billed with reference to the delivery.
• Component Item Category TAE:
  • Pricing (PRSFD) = ' ' (Blank): Components carry no price, which prevents double billing.
  • No goods movement: Components are explanation items. They can be copied into the delivery for information, but no goods movement is posted for them.
  • Billing Relevance (FKREL) = ' ' (Blank): Components do not appear as billed lines on the invoice.

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Model 2: Component-Level Pricing (Item Category Group LUMF)

In the LUMF model, the bundle represents a modular or customizable collection of items. The parent material serves primarily as a commercial shell or grouping header, while pricing, inventory valuation, delivery, and billing occur independently for each constituent component.

Customizing and Determination Mechanics:

1. Material Master: The parent material is assigned Item Category Group LUMF. Component materials carry standard Item Category Group NORM.
2. Header Item Determination (VOV4): $\text{Order: OR} + \text{Item Cat Group: LUMF} + \text{Usage: [blank]} + \text{Higher Item: [blank]} \longrightarrow \mathbf{TAP}$
3. Component Item Determination (VOV4): $\text{Order: OR} + \text{Item Cat Group: NORM} + \text{Usage: [blank]} + \text{Higher Item: TAP} \longrightarrow \mathbf{TAN}$

Operational Behavior of TAP and TAN in VOV7:

• Parent Item Category TAP:
  • Pricing Relevance (PRSFD) = ' ' (Blank): The parent item carries no commercial price.
  • No inventory management: TAP uses a schedule line category without inventory management (standard CT), so the main item can be copied into the delivery for information, but no goods movement is posted for it.
  • Billing Relevance (FKREL) = ' ' (Blank): The parent does not appear on the invoice as a billed line item.
• Component Item Category TAN:
  • Pricing Relevance (PRSFD) = 'X': Each component is priced independently using standard condition technique records. The customer pays $700 for the tower, $300 for the monitor, and $100 for the keyboard (total $1,100).
  • Schedule lines allowed: yes: Standard schedule lines (CP) are generated.
  • Item Relevant for Delivery = 'X': Physical goods issue occurs via movement type 601.
  • Billing Relevance (FKREL) = 'A': Each component is billed individually with reference to its delivery quantities.

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Side-by-Side Comparison: ERLA vs. LUMF

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Higher-Level Item Linkage in Table VBAP

When a Sales BOM explodes in transaction VA01, the system creates multiple records in database table VBAP (Sales Document Item Data). To preserve the hierarchical relationship between the parent bundle and its sub-components, SAP uses the Higher-Level Item field:

• Field VBAP-POSNR: The item number of the current line item (e.g., 000010, 000020, 000030).
• Field VBAP-UEPOS: The item number of the superior or parent line item.

Sales Order Line Items in Table VBAP:
Item (POSNR)  Material       Item Cat (PSTYV)  Higher-Level (UEPOS)  Description
────────────  ─────────────  ────────────────  ────────────────────  ───────────────────
000010        DESKTOP-KIT    TAQ               000000                PC Package (Parent)
000020        CPU-TOWER      TAE               000010                Tower Unit
000030        MONITOR-27     TAE               000010                27-Inch Monitor
000040        KEYBOARD-US    TAE               000010                Mechanical Keyboard

How VOV4 Uses Higher-Level Item Category During Explosion

When the user types DESKTOP-KIT on Line 10, the system determines item category TAQ. The system detects that DESKTOP-KIT has a sales BOM (usage 5) and executes explosion routines. When creating Line 20 for CPU-TOWER, the system queries determination table T184 with:

1. Sales Document Type = OR
2. Item Category Group = NORM
3. Item Usage = [Blank]
4. Higher-Level Item Category = TAQ (copied from Line 10's determined item category)

Because table T184 contains an entry for OR + NORM + [blank] + TAQ, the system determines TAE instead of standard category TAN. This higher-level linkage ensures that sub-items adopt the correct commercial role without manual user intervention.

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Multi-Item Logistics: Availability Check, Delivery Groups, and Billing

When the components themselves are delivered (the LUMF model), they can have different availability:

Delivery Groups (VBAP-GRKOR) and Correlation

If a customer orders a computer package priced per component, they typically do not want the monitor delivered on Monday, the keyboard on Thursday, and the CPU tower two weeks later. The bundle is useless until all components are present.

To prevent partial or fragmented shipments, SAP allows components to be assigned to a common Delivery Group (VBAP-GRKOR):

• When a delivery group is active, the system executes delivery date correlation.
• The ATP check evaluates the availability of every component in the group.
• The system synchronizes the confirmed delivery date of all group components to match the latest confirmed date among the items.
• Outbound delivery creation (VL01N) creates a single delivery containing all components simultaneously.

Invoicing Implications

• In the ERLA model, the main item TAQ is delivered and goods issued as one material, and it is billed at the kit price on a single invoice line. The components TAE appear only as information.
• In the LUMF model, each component TAN is delivered and billed with its own price. If components ship on different dates in separate deliveries, the customer receives separate invoice lines (or invoices) for what was actually delivered, unless a delivery group keeps them together.