PHPDoc

Use PHPDoc rules for formatting:

/**
* functionName
* 
* Brief description of the function. What it DOES,
* not how it does it
*
* @param   string  $name   The name of the user 
* @param   int     $age    The age of the user 
* @return  string          The generated welcome message 
*/
function functionName($name, $age) 
{ 
   ...
}

Pretty simple really.