The Standard Numbering System (SNS) consists of groups of characters (numbers or upper-case letters) separated by dashes. The first group of two or three characters is the system code, the second group, rather confusingly, has one character for the sub-system and another for the sub-sub-system code and the final group of two or four characters is the assembly code, e.g. XX-XX-XX or XX-XX-XXXX
Once again component manufacturing shows its strong influence on the specification. One way to make sense of this is to think of the three groups in terms of chapter, section and subject. The Knowledge Warehouse content already had a number of top level headings which could be thought of as chapters, which themselves were divided into sections, so this seemed at first a straightforward mapping. It also highlighted an important point, which is the relationship between the content in the repository and what is seen by the viewer. While S1000D advocates a modular approach, meaning content can be re-used anywhere, it is also important to consider that authors need to be able to locate the content quickly in the CSDB. Having a numbering system that means something is one way to achieve this. If an author knows they want to edit a procedure and all of the procedures are in chapter 1 which has a SNS starting 01 then this makes locating the content in the repository much easier than if a randomly allocated number is used. It was also discovered that having to consider a new numbering system prompted a rethink of how the airline’s engineering content was structured. For example, several chapters contained a section on health and safety. While some of this content could be re-used in a modular way, some was unique to the context of the chapter. It was decided to use the same section number to signify health and safety in each chapter so that authors knew immediately where to find health and safety content, as shown below:
01-02-XXXX – Health and safety section in chapter 1
02-02-XXXX – Health and safety section in chapter 2
Table 5. A word of advice..
| With hindsight, perhaps it would’ve been even better to put all Health and Safety content under a common code, maybe using HS as the system identifier and forgetting about the chapter context all together. In truth, there are many different and equally valid ways to organise content in S1000D and in the end it is for those who will be using the system to decide what works for them. |
Another important factor to consider is allowing space for the content to grow. For this reason it was decided quickly to use 4 characters for the assembly (or subject) code so that no artificial constraints were created early on in the project.
Similar restrictions exist on the total number of chapters and sections available, depending on whether it is decided to use numbers only or letters as well. Whatever system is chosen it is important to ensure that there is plenty of growing room at every level.