· Software: ‘A combination of associated computer instructions and computer data definitions required to enable the computer hardware to perform computational or control functions’. Like documents, software may appear within a configuration structure and may itself be subject to the CM process. The conceptual state of software is the source code and the linked external library and component. Its realised state is the executable application and the related files.
To fully define a complex product (Physical Product, Document or Software) it is often necessary to define the components from which it is made. In a generic structure we may identify one top element (the root), elements that are nodes of the tree and that are composed of other nodes, and basic elements, the leaves, that are not further decomposed. The tree structure is a directed acyclic graph (DAG), that is, a collection of nodes and directed links such that no node is an ancestor or descendant of itself.
The content of a product structure is dependent on purpose, viewpoint and context.
For example, if a product structure is aimed to support the Bill Of Material Structure, the basic elements (leaf) may be the equivalent of Part as defined by IEEE Std 1220-1994: ‘the lowest element of a physical or system architecture, specification tree, or system breakdown structure that can not be partitioned without destruction or impairment of designed use (e.g. bolt, nut, bracket, semiconductor, computer software unit)’
In the context of Configuration Management, the level of granularity of products attached to the leaves depends on viewpoint.
For example, let us assume that the main contractor decides not to maintain configuration control of an engine supplied by a subcontractor. In this case, from the contractor point of view, the engine is a leaf in the tree structure. From the subcontractor point of view, the same engine is the root of its tree structure.
 |
Product identifiers during the life cycle are assigned by different organizations.
For example, the user organization normally assigns its own identifier (e.g. tail number, plate number) to End Items for the purpose of tracking them. User-defined identifiers (e.g. NATO Stock Numbers) are assigned to Parts and Assemblies when these items need to be managed by the user stock management system.
It is essential that links between different identifiers of the same product are consistently maintained throughout its the life cycle.
To deliver effective CM it must be possible to uniquely identify all products.
A product identifier is an alphanumeric string attached to the product for the purpose of providing an absolute identifier that is guaranteed unique within a defined context. The product Id shall be independent of where the product may be used.
For the purpose of unique identification within PLCS, a three-layer model for product identification is used. This model is applicable to physical product as well as documents and software.
The top layer of the model consists of the Organization assigning the product identifier. Organizations should be classified in accordance with ISO 6523.
The middle layer is the Name Space Convention. This is used to identify the naming rules to be adopted (e.g. web addresses) and is provided by the parent Organization.
Уважаемый посетитель!
Чтобы распечатать файл, скачайте его (в формате Word).
Ссылка на скачивание - внизу страницы.