Final answer:
To display a three-letter abbreviation for the day of the week, the placeholder 'ddd' should be included in the date's format string. This works in programming languages and libraries that use date element formatting, although exact syntax can vary.
Step-by-step explanation:
To indicate that the three-letter abbreviation for the day of the week should be displayed, include 'ddd' in the date element format argument. For example, in programming languages like Python or Java that use date formatting, specifying 'ddd' within a date format string will display the abbreviated form of the weekday, such as 'Mon' for Monday, 'Tue' for Tuesday, and so on.
In contexts where you are working with SQL databases or other date formatting libraries, the syntax may differ slightly, but the concept remains the same – a place holder is used in the format string to represent the desired output format for the date. Always refer to the documentation of the specific programming language or library you are using for the precise syntax.