The BOM Procedure

Missing Values in the Input Data Sets

The following table summarizes the treatment of missing values for variables in the input data sets used by PROC BOM.

Table 3.6: Treatment of Missing Values in the BOM Procedure

Data Set	Variable	Value Used/Assumption Made/Action Taken
Part Master	`ID`	Missing, if `Part` is not missing;
		otherwise ignored
	`LeadTime`	0, if `Part` is not missing;
		otherwise ignored
	`Part`	Value ignored
	`QtyOnHand`	0, if `Part` is not missing;
		otherwise ignored
	`Requirement`	Ignored if `Part` is missing;
		1, if `Part` is not missing and the item identified by the `Part` variable is an end item;
		otherwise, the value is determined by the procedure
Product Structure	`Component`	Value ignored
	`Factor`	0, if corresponding `Component` variable is not missing;
		otherwise ignored
	`Offset`	0, if corresponding `Component` variable is not missing;
		otherwise ignored
	`Parent`	Input error: procedure stops with error message, if this is the first observation;
		otherwise, the value of the `Parent` variable in the previous observation
	`Quantity`	1, if corresponding `Component` variable is not missing;
		otherwise ignored
	`RID`	Missing, if corresponding `Component` variable is not missing;
		otherwise ignored

Note that in the Product Structure data set, a missing value is allowed for the Parent variable only when two or more consecutive observations contain product structure records with the same parent item (see Output 3.1.1 and Output 3.3.2 as examples). In the Part Master data set, if the Part variable is missing, the values for the ID, LeadTime, QtyOnHand, and Requirement variables are ignored by the procedure. If the Part variable is not missing but the Requirement variable value is missing, the gross requirement of the item identified by the Part variable is assumed to be 1 if the item in question is an end item. Otherwise, the gross requirement of this item is determined based on the dependent demand process. See the section Summarized Parts Data Set for details about the dependent demand process.