When included in a hierarchy, the Components are position dependent for their meaning and applicability to the Bill of Material. The Bill of Material structure is broken down into three classifications or ways to represent the Item. An Item may be included by itself as in the first sub-grouping, or an Item may be represented as part of a set of options or as an option within a class of options. An example of an option would be CD-ROM for a laptop computer. Then each of the types of CD-ROM's for the option would be a separate Item. An example of an option class would be memory for a laptop. The options could then be 128, 256, or 512 megabytes of RAM. Each of these options would then have separate Item identifiers for memory modules that makes up the appropriate amount of memory. For 256 megabytes of RAM, this could be two 128 megabyte memory modules or one 256 megabyte. Information that generally describes the Bill of Material Structure and its contents. Information that describes the attributes of a specific Option within a classification. Information that describes the class of Option for a particular Product or Item Identifies the Items that the Bill-Of-Material creates. There may be other items created as a by-product of this same process. The first occurance is the primary Item of this BillOfMaterials. Identifies Alternate BillOfMaterials for the given BillOfMaterials. Identifies the quantity that can be produced in each run of the BillOfMaterials. Refers to the drawing position of a particular component in the DrawingAttachment on the header.