Basic Syntax: Functions

Functions
Every Smarty tag either prints a variable or invokes some sort of function. These are processed and displayed by enclosing the function and its attributes within delimiters like so: {funcname attr1="val1" attr2="val2"}.

Contoh

 * Both built-in functions and custom functions have the same syntax within templates.
 * Built-in functions are the inner workings of Smarty, such as {if}, {section} and {strip}. There should be no need to change or modify them.
 * Custom functions are additional functions implemented via plugins. They can be modified to your liking, or you can create new ones. {html_options} is an example of a custom function.

Sumber
https://www.smarty.net/docs/en/language.syntax.functions.tpl