It is super useful to have the CSS and JavaScript files loaded with a ?ver=1.2.3 query parameter:
– /wp-content/plugins/jquery-validation-for-contact-form-7/css/jvcf7_validate.css?ver=1.2.3
instead of
– /wp-content/plugins/jquery-validation-for-contact-form-7/css/jvcf7_validate.css
This allows for some good caching to be applied to all files with a ?ver parameter. Once the plugin is updated, the version is increased and all old caches are invalidated.
This works by using the wp_register_style
PHP function and providing a version.
(This issue has been reported before at https://wordpress.org/support/topic/use-versioned-urls/)