Go to Master Data > Finance > Print texts.
The overview displays the maintained print texts. The reason code is predefined by Scope.
Available Reason Codes
Editor
In the editor, you can modify existing entries or add new entries as needed.
Reason Code
The reason code is determined automatically by Scope based on the document’s taxability.
Print Code
The print code is the abbreviation that appears on documents next to the cost type.
Default Text
The standard text appears as a legend accompanying the print codes used.
New (button)
With New, a new localization is created.
Example
In this example the reason codes (print codes) P and DT are used: 
Scope appends the corresponding print code to each entry and displays the maintained text as a legend.