Define Substitution:
With Substitution, you can define the correct value in a particular field. This happens in the background. Substitution happens for all the accounting documents for which the said prerequisite statement satisfies. Substitution changes the value in that particular field, if it contains any data. This happens even when you change the document also. So, be cautious while designing the scenario in relation to substitution.
A substitution step contains the following statements:
• Prerequisite statement:
a. The prerequisite statement establishes which conditions must be fulfilled before the substitution can be performed.
i. If the prerequisite statement is false, the transaction is continued without substitution.
ii. If the prerequisite statement is true, the transaction is continued with the substituted values.
• Substitution value(s):
b. The substitution value is a numerical value or a string of letters that replace the value entered.
c. A single substitution process can replace more than one value.
• Substitution exit:
d. You can specify that substitution is to be performed through a substitution exit.
e. The substitution exit number directs the system to an ABAP program defined by the user.
f. Substitution exits enable you to define more complex substitutions and replace more than one value in a substitution.
g. The prerequisite statement used in a substitution can consist of a simple statement or a complex combination of statements composed of logical statements, rules, and sets.