When you declare a mapping parameter or variable in a mapping or a mapplet, you can enter an initial value. The Integration Service uses the configured initial value for a mapping parameter when the parameter is not defined in the parameter file. Similarly, the Integration Service uses the configured initial value for a mapping variable when the variable value is not defined in the parameter file, and there is no saved variable value in the repository.

When the Integration Service needs an initial value, and you did not declare an initial value for the parameter or variable, the Integration Service uses a default value based on the datatype of the parameter or variable.

The following table lists the default values the Integration Service uses for different types of data:

For example, you create a new mapping using an Integer mapping variable, $$MiscellaneousExpenses. You do not configure an initial value for the variable or define it in a parameter file. The first time you run a session with the mapping, the Integration Service uses the default value for numeric datatypes, 0.

Or, if you create a mapping parameter $$MiscellaneousCosts to represent additional expenses that might become relevant in the future, but do not currently exist in source data. You configure the parameter for a Decimal datatype. Since you want $$MiscellaneousCosts to evaluate to 0 when you do not have additional expenses, you set the initial value to 0.

As long as you do not define the parameter value in the parameter file, the Integration Service replaces $$MiscellaneousCosts with 0. When you want to include miscellaneous expenses in mapping calculations, set $$MiscellaneousCosts to that value in the parameter file.