Display expressions actually represent superset of standard attribute expressions. Major difference is that they're always evaluated to a string value, suitable for displaying as feature annotations (or labels). Another difference is that they support advanced value formatting parameters.

Feature property keywords use square brackets:

[PropertyName]

Feature property formatting uses .NET formatting notation:

[PropertyName;FormatString]

Expression contents outside of square brackets ([]) evaluates as literal text:

"This is: [PropertyName]"

Expression contents inside the square brackets ([]) evaluates as function or variable:

[if(PropertyName=1,'A','B')]

If there's a [...;FormatString] expression formatting set, the value is explicitly cast to Double type.

Available expression format strings:

• Standard numeric format strings
• Custom numeric format strings
• Standard date and time format strings
• Custom date and time format strings
• General formatting table/chart