add_meta_box() – Adds a meta box to one or more screens. WP Function.
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add_meta_box() – Добавляет дополнительные блоки (meta box) на страницы редактирования/создания постов, постоянных страниц или произвольных типов записей в админ-панели.
add_meta_box breaks post preview · Issue #15404 · WordPress/gutenberg · GitHub
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CREATING ADDITIONAL FIELD IN YOUR POST IN WORDPRESS wp_nonce_field(), get_post_meta(), add_meta_box() | armantutorial
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add_meta_box() – Adds a meta box to one or more screens. WP Function.
add_meta_box breaks post preview · Issue #15404 · WordPress/gutenberg · GitHub
php - WordPress: CPT Adding Multiple Meta boxes, only saves the value of the first metabox - Stack Overflow
WordPress Add_meta_box to Custom Post Type
add_meta_box not working · Issue #7738 · WordPress/gutenberg · GitHub
