This is a way to format strings, such as decimal numbers and such. Use the syntax for sprintf() for the formatting.
Example 5-17. string_format
<?php$smarty->assign('number', 23.5787446);?>
Where template is:
{$number} {$number|string_format:"%.2f"} {$number|string_format:"%d"}
This should output:
23.5787446 23.58 24
See also date_format.