Electronic Parts Catalog and Service Parts Databases

What Is the Difference?

It’s only though a discussion with a vendor of “electronic parts catalogs” that we understood that this is the most common nomenclature used to describe what we describe as a service parts database. We cover service parts databases in this post below.


Electronic parts catalogs are complex and have special needs in terms of supersession and detailed service information. Companies like Enigma, combine pure content management (which is a very broad field which incorporates the storage of almost any organized form of readable data) along with procurement decision support, among other functionalities. This type of functionality actually dovetails with bill of material or BOM management software – one example of which is Arena Solutions. However, while BOM management software is primarily used before and item is made, service parts databases (SPDBs) or electronic parts catalogs (EPCs) are used after the products are deployed and ready to be ordered. There is a good reason to integrate the system. As a test case we have attempted to do just this with our service parts portal, which is a simplified service parts database which integrates real time with an Arena Solutions demo system. The web technology of widgets, allows one web page to display the content of other HTML based systems through screen scraping. (we discuss the importance of making 100% web interface supply chain software in this post)


Service Parts Portal

We have taken advantage of this technology to produce the demo that you can see at the page listed below. (it comes with its own demo video, which we have included below as well.


The integration above is not implemented nearly enough.

This video is available on the Service Parts Portal site as well.

The Logical Integration

The reason integration it is necessary is because it is important to have new parts, part supersession, and other changes reflected in the EPCs so that the correct parts are ordered. However, PLM (collaborated on by designers, manufacturing and suppliers) has been considered a separate system from EPCs (collaborated upon by parts managers, dealers, and inventory planners).


Understanding Service Parts Planning



Generally service parts planning differs from final product planning in the following ways:

  1. A high number of low volume irregular demand items in the planning database
  2. Inapplicability of traditional measures of forecast error (service parts management has much higher month by month forecast error than finished good forecasting. A service part can go many months with no demand at a product/location)
  3. A higher necessity to manage many locations as a single inventory “pool” – this means more transshipments between various inventory holding locations
  4. More complexity in procurement (end of life, lifetime buy, phased out suppliers) leading to different inventory holding strategies
  5. High variability in repair lead times (due to un-serviceable items which require inspection prior to repair lead time estimation)
  6. Inapplicability of common high volume forecasting and inventory management techniques (such as high volume forecasting algorithms and EOQ or POQ)
  7. Higher emphasis and need to handle obsolescence supersession and substitutability.

Supersession and Interchangability in SAP

What is Part Supersession?

Supersession is one of the most important functions in any service parts planning system. Supersession is used to both:

  1. Substitute one part for another part
  2. Obsolesce parts due to engineering changes driven by PLM (Product Lifecycle Management) that need to be replaced by newer versions

The supersession configuration in service parts planning systems allows this to be performed automatically during the planning. In MCA SPO this supersession is handled by configuring whether the part is subject to supersession and the type of supersession (One Way or Two Way that applies). We will use the description of supersession in the MCA Service Parts Optimizer Glossary of Terms:

Supersession in MCA

Used to specify that a Part should be replaced with a different Part (referred to as a Planned Part). Supersession processes are part of the forecasting batch process. They transform demand, population and inventory data to reflect it on the currently planned versions of the Part. Three types of supersession processes are performed on data within SPO: Demand Supersession, Contract Population Supersession and Inventory Supersession – MCA Glossary

Supersession Type

Indicates the type of Supersession applicable to a Part. This value (ONE-WAY or TWO-WAY) is used to determine if inventory of the superseded Part can be used for satisfying demands for the superseding Part. Inventory of TWO-WAY superseded Parts is added to the inventory of their superseding Parts, whereas inventory of ONE-WAY superseded. – MCA Glossary

Supersession in SAP

When an external system that is specialized for service parts planning tells SAP what to do, SAP can simply execute the recommendations made by the external system. However, the question arises what SAP ECC’s capabilities are with supersession.

According to SAP web sources, supersession resides in:

  1. Advanced Planning and Scheduling (in SCM)
  2. Supply Chain Management
  3. Service Parts Management (within SCM)
  4. In ECC

Supersession in SAP SCM/APO

SAP documentation states that its SCM module has supersession capability. However, the SAP Service Parts Planning solution is so lightly installed (as of mid 2007) that it does not well represent the supersession capability on a typical SAP install, specificially SAP ECC. However, outside of SPP, APO has supersession (called substitution or interchangability outside of service parts). The way to arrive at it as of SCM 5.0 is to goto

APO – Master Data – Application-Specific master data – Product and Location Interchangeability – Maintain Interchangeability group

You can apply the substitution here or if you are using CTM, in the CTM profile. (see our sister blog for an explanation of CTM)


This is fairly simple, you can see from the screenshot that we have populated the following information:

  1. The Group Type (supersession chain)
  2. The Group name – SNAPP_GROUP
  3. The Group description
  4. What the supersession is relevant for (for both planning and ATP)
  5. Next set the preceding part and the succeeding part

Finally we save this and we will have just created an Interchangeable Group.

Next I need to assign a location. What this means is we can create supersession relationships that just apply for particular locations but not for others.

We have not been able to verify this, (as we presently lack access to a SCM 2007 aka SCM 5.1 system), however the functionality of supersession – interchangability has been enhanced and is now located at:

Advanced Planning and Optimization (SAP APO) – Service Parts Planning (SPP) – Master Data and General Functions for SPP – Product Interchangeability in SPP

The enhancement relates to the ability to use form fit function classes in addition to product supersession. “That is you can define a product as the leading product for each subgroup of a form fit function class. DRP then consolidates the demands and stock of the location products by adding the demand and stock of the non-leading location products with substitute orders to the demand and stock of the leading location product. – SAP SCM 2007 Release Notes

Supersession in SAP ERP

Within SAP ECC, supersession is approximated by the Material Determination functionality. However, within SCM, SAP states that the rule based Available to Promise check does provide this functionality. In ECC product substitution functionality is called Material Determination (MD). The SAP definition of Material Determination is:

Material determination enables the automatic substitution of materials in sales documents during sales order processing. For example, during the course of a sales promotion, the system can, during sales order entry, automatically substitute a material that has promotional packaging. A consumer product may have a special wrapper for, for example, the Christmas season. Using material determination, the system substitutes the material only during the specified period. Material determination is used for:

  • Customer-specific product numbers with your own material numbers
  • International Article Numbers (EANs) with your own material numbers
  • Substituting discontinued materials with newer materials” – SAP Help

Interesting features of material determination

  1. MD happens during the sales order process
  2. Sales document types (A&D Contract, Repair Quotation, etc.) can be set for MD

This screen shows the connection settings between the Sales Doc Type and Material Determination

Where Should Supersession be Performed?

Supersession logic can be maintained in both the planning system and the execution system. That is both in MCA and SAP. They can be for different purposes however. A few options are:

  • Planning supersession can be performed in MCA, while execution supersession can be performed in SAP ECC (for sustainment, production supersession is a different matter).
  • Planning supersession can be performed in MCA with no sustainment supersession data maintained in SAP ECC. However inventory planners can still use MCA’s user interface to determine the superseeded part, and then execute the supersession in SAP.

In either case SAP will respect the supersession that is performed in SAP as it would be inherent in the New Buy List that came from MCA. The basic questions are:

  1. Is having the execution supersession available in SAP (allowing automated supersession within SAP ECC) worth the additional effort in configuring MD and in the continual maintenance of this supersession list in SAP?
  2. Is the MD functionality capable of providing similar functionality as comes with MCA? That is, is the substution functionality, which is fairly basic, and which would provide automated supersession worth maintaining instead of looking at the MCA user interface and reading supersession relationships from MCA?

Supersession in SAP Documentation

The document below from SAP is light on details.


The best write up on supersession in SAP that we have seen is at: