A mixed number range is available in some rare cases such as document management. This type of number range, when available, permits the user to provide a prefix in the number field, after which the system assigns a sequential number.
If there is an inclination to use external (user specified) numbering, try to restrict it to more static data, such as equipment. For transaction-related
data, such as work orders, it is often more beneficial to allow the system to assign the numbers.
Both internal and external number ranges can sometimes be active for the same items at the same time. In fact, it is possible, and in some cases prefer-able, to have more than one of each type of number range active at the same time, although it is not necessarily preferable to define internal and external number ranges for the same item. For example, different equipment cate-gories can be assigned different number ranges. Alternatively, the equipment categories could share the same number range or a combination could be defined where some equipment categories share a number range and others are assigned their own number range. Multiple number ranges could be used if there is a reliance on “smart” numbering where the number of an object shows the type/category of the object. As discussed in more detail below, the more number ranges that are defined, the more consideration must be taken to avoid running out of numbers in any of the ranges.
When planning a number range, take into consideration all possible scenar-ios that could affect the future demands on the number range. When defin-ing a number range for work orders, for example, consider how many work orders are used at each location, how much the number of work orders is expected to increase, whether work orders will be used for new types of work, whether other locations will be added through expansion or acquisition, and so on. Define the number range to be large enough to accommodate any foreseeable circumstances.
When naming a number range, make the description as meaningful as possi-ble, given the space available for the description, especially in the case of number ranges that are shared between modules, such as the order number range. It can also be helpful, if space is available in the description, to include the “from” and “to” numbers of that range. This makes it a little easier to see at a glance what number ranges have been set up.
Some number ranges are “shared” by more than one module and should be configured in co-operation with other modules. The most notable shared number range table is the number ranges for orders. While used in Plant Maintenance for work orders, the same number range table is also used by other modules, for example, CO (Controlling) for internal orders, SD (Sales and Distribution) for sales orders, PP for production orders, and so on. Do not delete or make adjustments to shared number ranges without knowing the effect on other modules.
While it is possible to transport number ranges to other instances (systems), it is not easy to do so and it is strongly discouraged. When changes to a num-ber range are made, a warning to that effect normally appears. The main rea-son is that internal number range configuration also includes a current number, which enables the system to determine the next available number.
One potential problem is that the current number on the source system (transporting from) is lower than the corresponding current number on the target system (transporting to). When the lower current number is trans-ported, the system will then attempt to assign a “next” number that has already been used, with the possibility of corrupting the data. Number ranges should be configured manually on each instance (system).
Refer to the SAP documentation regarding the definition of each type of number range, paying particular attention to the reasons for creating addi-tional number ranges. For example, it is generally not a good idea to create different work order number ranges for different plants.
The steps usually involved in defining number ranges are:
1. Determine whether the number range is specific to Plant Maintenance or shared with other modules. Be considerate of other modules’ requirements, current and future, when a number range, such as that for orders, is shared.
2. Determine the groups (separate number ranges) that will be required.
3. Determine whether internal (system-assigned) or external (user-assigned) number ranges will be required.
4. Determine the ranges that are available for numbering and plan for the ranges to be defined.
5. Determine the quantity of numbers required for each number range.
Allow for that quantity and then add a substantial quantity more.
6. Determine whether the types of objects should each have their own number range or whether they should share a number range. For example, does each equipment category require its own number range or can equipment categories share number ranges?
7. Define the group(s) required to contain the number range(s).
8. Define the number ranges, if more than one, non-consecutively.
That is, leave space between each number range to accommodate the
extension of a number range, if required in the future. If exception-ally good planning was used in determining the number ranges, of course leaving such space is optional.
9. Assign the object types (equipment category, for example, if defining number ranges for equipment) to the appropriate group(s). This can be performed by double-clicking on the object type(s) (their color will change), checking the box beside the appropriate group, and then clicking on the Element/Group button . Note that the object type—equipment category code, for example—
will appear at first at the bottom of the screen (scrolling down may be required) in a “group” that may have the title “Not Assigned.”
10. When saving number range configuration, a window will appear, containing information that number range configuration will not be transported automatically. As previously discussed, it is generally not a good idea to transport number ranges, although a transport can be initiated manually. If number ranges are transported, be completely aware of the numbering, particularly “current numbers, ” that will be affected by the transport.
As discussed previously, numbers may or may not be “buffered.” Buffering numbers causes several numbers, the exact number depending on the buffer settings, to be retrieved from the database in advance. Doing so can save some time in the long run, since the system does not have to access the data-base each time a number is required. It can also, in some cases, help to avoid delays caused by “locks” when people or programs attempt to access the same numbers at the same time. On the other hand, if numbers are buffered, they may be lost if the system stops running unexpectedly. For example, if the equipment number range is buffered to retrieve 10 numbers at once and the system stops unexpectedly after the first two pieces of equipment, numbered 1 and 2, are saved, the next piece of equipment, when the system recovers, may be saved with the number 11.
If it is critical that numbers be sequential without gaps, ensure that buffering for that number range is turned off. If it is not critical that numbers be sequential without gaps, it may be beneficial to allow buffering.
Buffering number ranges or turning buffering off is usually performed by the Basis team.