Editing Structured program theorem (section)

==Application to Cobol==
{{More citations needed section|date=August 2013}}
In the 1980s [[IBM]] researcher [[Harlan Mills]] oversaw the development of the [[COBOL Structuring Facility]], which applied a structuring algorithm to [[COBOL]] code. Mills's transformation involved the following steps for each procedure.

#Identify the [[basic block]]s in the procedure.
#Assign a unique [[Label (programming language)|label]] to each block's entry path, and label each block's exit paths with the labels of the entry paths they connect to. Use 0 for return from the procedure and 1 for the procedure's entry path.
#Break the procedure into its basic blocks.
#For each block that is the destination of only one exit path, reconnect that block to that exit path.
#Declare a new variable in the procedure (called L for reference).
#On each remaining unconnected exit path, add a statement that sets L to the label value on that path.
#Combine the resulting programs into a selection statement that executes the program with the entry path label indicated by L
#Construct a loop that executes this selection statement as long as L is not 0.
#Construct a sequence that initializes L to 1 and executes the loop.

This construction can be improved by converting some cases of the selection statement into subprocedures.