Indented Bills of Material Data Set

The BOM Procedure

Indented Bills of Material Data Set

The Indented BOM data set produced by PROC BOM contains all the information in the Single-level BOM data set, plus a few more variables, to describe the structure of the products. The Part, LeadTime, Quantity, and all ID variables in the Single-level BOM data set are carried to this output data set. The name of the Part variable is changed to _Part_. Moreover, if there is more than one Quantity variable in the Single-level BOM data set, the procedure uses the name Qty_Per as the Quantity variable in the Indented BOM data set. Like the Single-level BOM data set, the information contained in those variables is associated with the item identified by the _Part_ variable. A few new variables are also added to the Indented BOM data set.

The _Level_ variable contains the indenture level of the item identified by the _Part_ variable. The top-most parts (the final products) have level 0, and all components that are directly used by these parts have level 1. All subsequent components of those items have the level number increased by 1. This process continues until there are no subsequent components. The _Parent_ variable contains the part name or number of the parent item. The _Prod_ variable contains the part name or number of the final product in the product structure. If the input data set contains the lead time information for each part, PROC BOM measures the total lead time accumulated from the final product (identified by the _Prod_ variable) to the part (identified by the _Part_ variable) and puts it in the Tot_Lead variable. The Qty_Prod variable denotes the quantity of the part (identified by the _Part_ variable) required to make one unit of the product identified by the _Prod_ variable.

Two more variables are added to the output data set: variable Part_ID and variable Paren_ID. Note that if an item is used in more than one parent item, it appears more than once, under every subassembly in which it is used. In order to distinguish those parts that have multiple appearances, PROC BOM assigns a unique number to each part in the multilevel tree structure. The Part_ID variable contains this identification number of the part (identified by the _Part_ variable), and the Paren_ID variable contains the identification number of the parent item. These two variables are useful when you use the Indented BOM data set as the input data set for other SAS/OR procedures, such as PROC NETDRAW and PROC CPM, which require unique identification of each node.

Table 1.3 lists all of the variables in the Indented BOM data set. It also lists the type and a brief description of these variables.

Table 1.3: Indented BOM Data Set and Associated Variables

Variable	Type	Interpretation
ID	character or numeric	Additional information about the part
LeadTime	numeric	Lead time of the part
_Level_	numeric	Level number of the part
_Parent_	same as _Part_	Parent item of the part
Paren_ID	numeric	Identification number of the parent
_Part_	character or numeric	Part name or number
Part_ID	numeric	Identification number of the part
_Prod_	same as _Part_	Name or number of the final product
Qty_Prod	numeric	Quantity required to produce one unit of
		final product
Quantity	numeric	Quantity per assembly
Tot_Lead	numeric	Total lead time

The records in the Indented BOM data set are organized so that the final product item is always listed first. In addition, each item is listed directly after its parent and before any right siblings of the parent. For example, from the Indented BOM data as shown in Figure 1.3, you can easily see that the final product `LA01' is the first record of the Indented BOM data set. Moreover, the part `1700' is listed directly after its parent, `A100', and before the parts `S100' and `B100' (the right siblings of the part `A100'). The single-level (part-component) and multilevel relationships of the product structure are clearly shown in the Indented BOM data. For example, the three components that go into the parent `LA01' are easily determined by the level 1 identifiers. It is also easy to see that the part `B100' (Base assembly) requires four components at level 2.

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