phpdoc standard for setting default value of an optional parameter?

Example:

/**
 * This function will determine whether or not one string starts with another string.
 * @param string $haystack <p>The string that needs to be checked.</p>
 * @param string $needle <p>The string that is being checked for.</p>
 * @param boolean $case[optional] <p>Set to false to ignore case(capital or normal characters)</p>
 * @return boolean <p>If the $haystack string does start with the $needle string, the return will be true. False if not.</p>
 */
function endsWith($haystack,$needle,$case=true) {
    if($case){return (strcmp(substr($haystack, strlen($haystack) - strlen($needle)),$needle)===0);}
    return (strcasecmp(substr($haystack, strlen($haystack) - strlen($needle)),$needle)===0);
}

The optional parameter is set to true by default. I wish to indicate what the default setting is in the documentation. Is there a standard way of doing this or do I have to mention it in the description?