modifed core and new filter for non-class related body elements

body-class-elements.php

// filter inside theme or plugin

function schema_bodyitems($item) {

	$item[] = 'itemtype="http://schema.org/Blog"';
	$item[] = 'itemscope=""';
	
	return $item;
}

add_filter('body_items','schema_bodyitems');

// core function addition to get said items

function get_body_items($item_array = '') {
	
	$item = array();

	$item_array = apply_filters( 'body_items', $item);

	if(empty($item_array))
		return $items;

	$items = ' '.join( ' ', $item_array );

	return $items;
}

// modified core function

function body_class( $class = '' ) {

	$items = get_body_items();

	// Separates classes with a single space, collates classes for body element
	echo 'class="' . join( ' ', get_body_class( $class ) ) . '"'. $items;
}