PHP Manual: MongoDB\BSON\Binary::_

final public function MongoDB\BSON\Binary::__construct(string $data, int $type = MongoDB\BSON\Binary::TYPE_GENERIC)

data (string): Binary data.
type (int): Unsigned 8-bit integer denoting the data's type. Defaults to MongoDB\BSON\Binary::TYPE_GENERIC if not specified.

Version	Description
PECL mongodb 1.15.0	The `type` parameter defaults to `MongoDB\BSON\Binary::TYPE_GENERIC` if not specified.
PECL mongodb 1.3.0	MongoDB\Driver\Exception\InvalidArgumentException is thrown if `type` is `MongoDB\BSON\Binary::TYPE_UUID` or `MongoDB\BSON\Binary::TYPE_OLD_UUID` and `data` is not exactly 16 bytes in length.
PECL mongodb 1.1.3	MongoDB\Driver\Exception\InvalidArgumentException is thrown if `type` is not an unsigned 8-bit integer.

Example #1 MongoDB\BSON\Binary::__construct() example

<?php

$binary = new MongoDB\BSON\Binary('foo', MongoDB\BSON\Binary::TYPE_GENERIC);
var_dump($binary);

?>

The above example will output:

object(MongoDB\BSON\Binary)#1 (2) {
  ["data"]=>
  string(3) "foo"
  ["type"]=>
  int(0)
}

MongoDB\BSON\Binary::__construct