Expression examples Examples of common expressions used by report designers. Check a field for a value Check whether a field contains a value, is empty, or is null and act accordingly. Change the display based on a condition Change the way your report displays depending on a condition in the RTL expression. Display an image based on a variable Check the value of a variable and display the image specified by the variable. Size a column based on data Base the size of a column on the size of the translated text displayed in it. Format a number within a string Include a formatted number in a text string. Related concepts Using a page number string Custom keys