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Introduction to SAP GATP aka Global Available to Promise

ByShaun Snapp

Executive Summary

  • GATP is the availability checking module in APO, and it differs from standard availability checking in ERP.
  • We cover multilevel ATP checking, ATP categories, the Calculation Profile, performing a basic ATP check, the GATP Check Mode, and when the check is performed.
  • Why some supply chain experts question the implementability of GATP.

Introduction: Understanding GATP from Multiple Views

Companies use GATP to enhance their availability checking capabilities over ATP checks in ECC. You will learn multidimensional aspects around GATP, including real implementation experiences from the module.

What is GATP?

SAP GATP is one of the most peculiar and complex modules within the SAP APO suite. This article will explain the important aspects of GATP. There are many other articles on GATP on this website, and in fact, this article links out to a number of these articles as it deals with various topics. But this article can be seen as the general introduction and broad overview of SAP GATP.

How is SAP GATP Different from Standard Availability Checking?

The first question that often arises in regards to GATP is how it is different from availability checking, which is a functionality that is very familiar to anyone who has worked in SD or sales order processing. Therefore this is a good place to start in attempting to understand GATP availability checking. GATP offers many more alternatives than does SAP ERP with regards to availability checking
GATP offers much more substitution capability than SAP ERP availability checking.

This means that customers have a higher likelihood of being satisfied with the product, for a lower investment in inventory and productive capacity.

  • GATP offers better performance than availability checking in SAP EPR as it uses the liveCache memory system.
  • Different levels of hierarchy can be checked.
  • SAP ERP availability checking offers top level product checking, but GATP – if Multi-Level ATP is selected offers the ability to check availability at the component level.
  • GATP offers the ability to perform a global multi location check. (alternative location and product)
  • Availability checking is performed in SAP SD and is different from GATP in several important ways.
  • Availability checking provides a more simple response to a request than GATP.
  • GATP looks out across many different plant to attempt to fulfill a demand.
  • Outside of GATP, availability checking also occurs in EWM.

There are other differences, but this is a good starting point to determine if a GATP project is a strong opportunity at your company. If the list above is all highly desired, then the next step is to check on the likelihood of getting funding for a GATP project.

Ways of Running Availability Checking

There are several ways to run availability checking. Availability checking is a distinct functionality in SAP ERP, and GATP is a sub-type of the overall category called availability checking (somewhat confusing, we know).

GATP has a special form of availability checking called Capable to Promise (CTP), which entails connected GATP to PPDS. This is explained more fully here. However, few companies are ready for CTP, and in fact, it is a unicorn, therefore in most cases, the non-PPDS forms of GATP are implemented by companies. Interestingly, SAP covers CTP in its Help documentation; however, I have yet to see any live CTP instance in all my projects. However, because CTP is still discussed, it is often considered a possible option.

If “normal” GATP is selected, there are three different ways of running non-CTP GATP:

  1. Multilevel ATP Check
  2. Rules Based ATP Check
  3. Availability Checking for BOM or Kits

Scope of Check

  • Stocks (Safety stock, stock in transfer, Blocked stock, Restricted use stock, Subcontracted stock, Inspection stock)
  • Receipts or issue elements (POs, PRs, Dependent requirements, Reservations, Sales orders, Delivery notes, Shipping notifications, Dependent reservations, Call requirements, Production orders, Planned orders)

Multilevel ATP Checking

“..explodes the BOM structure of the finished product. The result of this ATP check are ATP tree structures that are created by the system when the sales order is saved in SAP APO. There is an ATP tree structure for each request schedule line in the sales order. An ATP tree structure contains, among other things, the requirements data (dates, quantities and sources of supply) for the required finished products and components.” – SAP Help

To understand more about the BOM and its use in SCM, see this article.

To see more about Availability Checking for BOM and Kits and how it interacts with the iPPE object, see this post. Of these alternatives, Multilevel ATP Check is the most complicated and best suited for assemble to order operations. Rules Based ATP Check is the most simple, while Availability Checking for BOM or Kits requires integration to CRM.

The Multilevel ATP Check is a user of ATP Trees. To find out more about these, see this article.

What are ATP Categories and How do They Relate to GATP?

Like SAP Capable to Match (CTM), GATP uses ATP categories to select demand and supply elements, in this case, for the ATP check, which is explained in this article. Furthermore, GATP works strongly with SAP CTM which computes the allocations from forecasts to inventory and then sends this information to GATP.

ATP categories are critical control items that are used throughout SAP APO as well as SAP ECC. More explanation on this can be found here.

SAP GATP SAP Menu Highlights

The areas that are available within GATP is limited, unlike other modules in APO. The major areas include the following:

  • Backorder Processing
  • Reporting
  • Environment
    • Technical Monitors
    • Product Availability
    • Product Allocations
    • Third Party Order Processing

A huge part of GATP is related to backorder processing. Backorder processing also exists in SAP SD. BOP, as referred to by SAP, list sales documents relevant for particular materials allowing for confirmation. Stocks can be assigned to outstanding orders. As evidence of how integrated GATP is to SAP ECC, as soon as one goes into creating a BOP worklist, which is transaction /SAPAPO/BOP_WORKLIST, the user is taken right into a login for ECC. This is very unusual for a module of APO to be so dependent upon ECC for fundamental operation. But as I explain further on, GATP is a strange APO module.

SAP GATP Configuration

Major Areas to maintain include the following:

  • Global Settings for Availability Check
  • Category
  • Business Event
  • Check Instructions
  • Correlation Profile
  • Advice Code
  • Number Ranges

SAP GATP and the Calculation Profile

This limits the processing in terms of how long the system can look forward and backward.  The calculation profile can include the following:

  • “Allowed delay
  • Allowed early confirmation: Accepted number days early
  • Consumption Limit: Number of days that prevents a requirement using receipt and stock that are too early.
  • Indicator Valid: Value maintained is taken into account in following checks.”

See this link for details.

Why is GATP Located in APO?

There is a question as to whether GATP should ever have been included in SCM. Here are the features of GATP:

  1. Must be up 24/7
  2. Is based upon planning results but is not in actuality planning functionality
  3. Must be able to look out and see future inventory positions
  4. It is a more comprehensive version of the available promise functionality that resides in SD. The order checking begins in SD when the order is tested.
  5. Unlike most of the modules in APO, SAP GATP does not have a processing procedure. For instance, in DP, a statistical forecast is generated. In SNP or PP/DS, an optimizer can be run, or heuristics can be run. GATP is not like this in that while it can be set up with rules concerning how far forward the global availability check runs, and the levels that it checks and the locations where it performs its check, the checking procedure is the extent of the “calculation” that is performed.

Why Does GATP Reside in APO?

Thus, along with the fact that so much GATP functionality and configuration is in SAP ERP SD, the question can be brought up as to why GATP sits in SCM/APO. Those that do configure GATP spend a great deal of time in ECC. Some propose that GATP is located in APO because this is profit maximizing as adding functionality to ECC cannot be charged to existing clients of ECC, and therefore GATP allows SAP to push companies to buy a new module. That is, it was marketing rather than an engineering decision. However, it is argued that the memory resident liveCache allows better results — however given that GATP is implemented most often in a very simply design, this argument seems a bit theoretical.

GATP shares many similarities with CTM, which is more logical and easier to understand. Thus a good place to begin to understand GATP is by studying CTM.

Product Availability Check Description

The book Supply Chain Management with SAP APO has a very good description of the product availability check, describing how pegging connects order objects at different levels. This is an explanation that is often left out of most evaluations of pegging. Here is the quote:

“The most obvious method of ATP is the product check, where the requirements are balanced with the receipts. This calculation is performed using time buckets of one day in the ATP time series live cache where all orders of a location product are stored with their quantities and their order category. These time series are displayed with the transaction category. These time series are displayed with the transaction /SAPAPO/AC05, whereas transaction /SAPAPO/AC03 already applies the scope of check (described in the following paragraphs) and filters the customized categories.”

Performing a Basic ATP Check

Below is an ATP check performed from within GATP.

Snap1

Here we are in the ATP check transaction within GATP. Notice that I have to declare the areas listed above. If no date is entered (in the Date/Quantity area), then the availability check is created for the current day. If not a future date can be entered, and the availability check will be run for that date. 

In this transaction, I have to tell it the product, the location, version, the check mode, and the business event. These two are important fields to call out.

Check Mode: This is explained at this link.

Business Event: The operations of a business. These are maintained in APO within SPRO underneath General Settings and then Maintain Business Event. The Business Event is made up of the following characteristics: 

  • Business Event Name
  • Business Event Text

Therefore, the Business Event is nothing more than its name and description.

The Type of ATP Check

The Check Mode combined with the Business Event determines the “type” of ATP check that is performed. However, because the real logic is maintained within the Check Mode, while the Business Event is necessary to populate, it is essentially an information field.

Snap2

After the green checkbox button is selected, we are taken to the ATP screen, which shows a vast quantity of stock that can be committed against any potential sales order. However, if a quantity is entered in the ATP screen, then the ATP check will only confirm that quantity. Notice below: 

Snap5

The second time I populated the quantity field with a value of 200, now the ATP has been performed for 200. Notice also that the date has been changed to 1/16/2016 rather than 12/31/2015. This is because I also changed the date of the ATP check. By double clicking this line item, one can be brought back into the ATP check setup. 

Next, we will view what is referred to as the check instructions by selecting the button at the screen’s top. Next, this screenshot comes up.

Snap3

These are all the options that appear for the Check Instructions. Notice that the Check Mode and the Business Event are right at the top of the screen.

When the Check is Performed

Next is when the check is to be performed: the Product Check, the Product Allocation that is against an allocation, or during Planning. These are the three basic types of ACs in SAP GATP. They are described as follows:

  • Product Avail Check: The description is not a useful one, because all ACs are obviously for a product. What this type of AC should have been called is a planned stock AC. It is against the planned stock. This is a time phased simple check and works basically the same as in SAP ERP. (and surprising to many, it is the most common way that GATP is implemented as the other methods described below end up being too complex to implement) APO > GATP > General Settings > Product Availability Check > Maintain Check Control is where this is set up.
  • Allocation Avail Check: The availability check against product allocations is the planned delivery date for the customer and not the material availability date. It is an AC against an allocation. The SAP definitions of allocations are very poor, but an allocation is an assignment between a demand element and a supply element. Allocations can come from CTM, or they can be inserted into GATP. This article describes a novel way of using allocations that are created in GATP to model supplier capacity. Actually, the entire topic of modeling allocations in GATP is confusing, and the previous article is a good place to start to understand it.
  • Planning Avail Check:

Rules Based Availability Check

Below this is the Rules Based Avail Check section. I found this definition from a link I provided in the references:

“An ordinary ATP check is restricted to the requested location product and checks only the according time series. Using Rules Based Availability Check(RBA or RBATP) it is possible to substitute both the location and the product. In branched supply chain networks, rules-based ATP allows companies to take full advantage of multiple shipping assets to ship goods from alternative sites to customers. In addition, it permits certain products to be substituted as required to successfully satisfy customer demands. This is a functionality available in GATP.” – SCN.SAP.COM

This is where the complexity of GATP really ratchets up, because there are so many options. Rules based AC has several configuration settings, which include:

  1. Maintain Field Catalog
  2. Product Allocation Object
  3. Product Allocation Group
  4. Product Allocation Procedure

There are so many areas to focus on; however, the Third Party Order Processing is of note. This allows processing to be performed against Contracts and Scheduling Agreements.

SAP GATP Check Instructions

These are maintained in APO within SPRO underneath GATP, General Settings, and then Maintain Check Instructions.

  • Check Mode: Identifier
  • Check Mode Text: Description
  • Business Event: Identifier
  • Business Even Text: Identifier
  • Product Check: Specifies when a product availability check (AC) should be carried out.
  • Type of Product Availability Check: Defines how the AC considers pegging relationships (Only Time Series, Only Fixed Pegging, Fixed Pegging then Time Series)
  • Type of Product Availability Check: Defines how the AC considers pegging relationships
  • Forecast: Determines if the AC will be performed against forecasts.

There are many more….however, it should also be understood that SAP’s Help has the incorrect information presented for many of the fields within the Check Instructions.

The GATP Check Mode

The Check Mode is apparent when selecting to perform a GATP availability check, as shown in the following screenshot.

Snap1

The Check Mode is below the Requirements Profile in the Check Control field group. 

The Check Mode comes from the Product Master, and therefore definable per product, and is the scope of the check that is performed combined with the forecast’s consumption. SAP SD uses the requirements class of the retirement in check mode; this RC is from the Strategy Group of the Product Location Master (ATP Tab). 

Four Characteristics of Check Modes

The Check Modes are made up of four characteristics, although in most cases, it is really three characteristics as rounding profiles are rarely used.

  • Assignment: None, to Planning with Assembly, to Planning without Assembly, to Planning Product
  • Product Type: Standard, Characteristic Evaluation, Multilevel ATP Check, Kit Check
  • Rounding Procedure:
  • Check Mode Text: Description

They are the following for the active Check Modes in the product that I have listed above:

  • 30 (No Assignment, Standard Product Type, No Rounding Procedure, Delivery Requirement)
  • 50 (Assignment Customer Requirement, Standard Product Type, No Rounding Procedure, Warehouse Consumption)
  • 200 (No Assignment, Standard Product Type, No Rounding Procedure, Assembly Planned Order)
  • CP1 (No Assignment, Standard Product Type, No Rounding Procedure, CP Food)
  • VMI (No Assignment, Standard Product Type, No Rounding Procedure, VM_SNC)
  • Y01 (No Assignment, Standard Product Type, No Rounding Procedure, SNC GATP)

The final characteristic is really more of the name or description of the Check Mode — that is what the Check Mode is used for. These are maintained in APO within SPRO underneath General Settings and then Maintain Check Mode.

The Problems with SAP GATP Documentation in APO and Generally

GATP is covered very poorly in publications outside of SAP Training manuals and SAP Help. (However, for some reason, both of these sources are confusingly written, and SAP Help contradicts itself on availability checking vs. GATP). For example, SAP gave up documenting fields, and therefore, many of the fields within one of the most important areas of GATP, called the Check Instructions, are copied over and over. All of this makes SAP GATP more difficult to implement. 

The published material shortage is surprising because GATP is one of the original SCM modules, so there has been plenty of time to document it. While not implemented as broadly as SNP or PPDS, we can not think of an excellent reason why so little is written on the module as it is a constant module of interest among clients. 

There is one book on SAP GATP. However, it describes many areas of functionality in GATP that I know very well are never implemented — for instance, it describes how GATP supports transportation and shipment scheduling to determine material availability — that does not happen. The SAP GATP will most often go off of lead times. Therefore the book is useful for finding out what is “standard” functionality in SAP, but it is utterly unreliable in explaining what does happen on implementations. I recall discussing a GATP book with SAP Press editors years before the book was written and I remember thinking that this would be a very challenging book to write. Furthermore, the number of options is so numerous in GATP. However, the actual implementation of the options is much different, leading to the next point. 

Contradictory Supply Chain Opinion on SAP GATP

Some supply chain experts dispute the implementability of SAP GATP because of some of the data, such as the shipping lead time accuracy. The complexity of looking out across many locations and other dependent variables related to future inventory is typically of insufficient quality to make GATP a worthwhile endeavor.

One complicating factor with GATP is its product-location planning and production scheduling, along with an order commitment and inventory allocation system all in one. Software that tries to do too much can end up not satisfying any of the requirements.

GATP is typically implemented by companies that are sophisticated SCM shops in general.

References

https://help.sap.com/saphelp_scm50/helpdata/en/73/b67337e68ac526e10000009b38f889/content.htm

https://help.sap.com/saphelp_470/helpdata/en/b1/c046db439a11d189410000e829fbbd/content.htm

https://scn.sap.com/community/scm/apo/production-planning-interfaces-and-global-atp/blog/2014/01/25/rules-based-availability-check-overview-and-stepwise-process-to-configure