Which command is used to format values without changing their characteristics?

The fieldformat command is utilized to change the display format of values in a search result without altering the actual data itself. This command allows users to define how specific fields should be presented visually, such as formatting numbers, dates, or other data types for better readability or presentation in reports and dashboards. It is particularly handy when you want to maintain the integrity of the underlying data while enhancing how it is perceived by end users.

Other commands, while they may manipulate data in some way, do not focus solely on formatting values without affecting their characteristics. For example, the eval command can transform data by calculating new values or changing data types, which does change the underlying value. Similarly, the modify command is used for altering data within the context of Splunk's configuration, and the formatvalue command does not exist in the context you're referring to. Hence, the fieldformat command stands out as the correct choice for the purpose of visually formatting values while keeping their original characteristics intact.