Invoke field.module's version of a field hook on multiple entities.
This function invokes the field_default_[op]() function. Use _field_invoke_multiple() to invoke the field type implementation, hook_field_[op]().
$op: Possible operations include:
For all other operations, use _field_invoke() / field_invoke_default() instead.
$entity_type: The type of entities in $entities; e.g. 'node' or 'user'.
$entities: An array of entities, keyed by entity ID.
$a:
$b: Currently always NULL.
$options: An associative array of additional options, with the following keys:
Internal use only. Do not explicitely set to TRUE, but use _field_invoke_multiple_default() instead.
An array of returned values keyed by entity ID.
function _field_invoke_multiple_default($op, $entity_type, $entities, &$a = NULL, &$b = NULL, $options = array()) {
$options['default'] = TRUE;
return _field_invoke_multiple($op, $entity_type, $entities, $a, $b, $options);
}