Key Value

import Screenshots from '@site/src/components/Screenshots';
The key-value field allows you to enter an unlimited group of "key-value" pairs. It's usually used for a list of items, such as a product specification.
Screenshots
<Screenshots name="key-value" col1={[
['https://imgur.elightup.com/yA7rRDR.png', 'The key value field interface']
]} />
Settings
Besides the common settings, this field has the following specific settings, the keys are for use with code:
Name
Key
Description
Placeholder
placeholder
Array of placeholder texts for key and value inputs. Format 
['key' => 'Key placeholder', 'value' => 'Value placeholder']. Optional.
This is a sample field settings array when creating this field with code:
[
    'id'   => 'key_value',
    'name' => 'Key Value',
    'type' => 'key_value',
    'desc' => 'Add more additional info below:',
],
Data
This field saves a serialized array of data of pairs in a single row in the database.
Template usage
Displaying list of key-value pairs:
<?php $pairs = rwmb_meta( 'my_field_id' ) ?>
<h3>Specification</h3>
<ul>
    <?php foreach ( $pairs as $pair ) : ?>
        <li><label><?= $pair[0] ?>:</label> <?= $pair[1] ?></li>
    <?php endforeach ?>
</ul>
or simpler:
<h3>Specification</h3>
<?php rwmb_the_value( 'my_field_id' ) ?>