How the Printed Value Is Determined
The actual text or value to be printed is specified as an expression in the .print statement syntax. The expression can be a column name, a constant, a function, an aggregate, a runtime report variable such as the current date and time, or a variable whose value is specified in a .declare or .let statement or on the command line, with or without a prompt.
By default, Report-Writer prints an empty string when it encounters a null value. You can change this default to any string of characters, using the .nullstring statement. For instance, you can tell Report-Writer to print the string "none" wherever it finds a null value in the data.
For more information on the .print and .nullstring statements, see Print Statements in the chapter "Report-Writer Statements."