wp-includes/post.php:8453Registers any additional post meta fields.
function wp_create_initial_post_meta() { register_post_meta( 'wp_block', 'wp_pattern_sync_status', array( 'sanitize_callback' => 'sanitize_text_field', 'single' => true, 'type' => 'string', 'show_in_rest' => array( 'schema' => array( 'type' => 'string', 'enum' => array( 'partial', 'unsynced' ), ), ), ) );}Introduced in 6.3.0. Unchanged from 6.7.7 through 7.1.0.
Signature, return type and hooks compared across 5 parsed releases.
src/wp-includes/post.php, and regenerated for each WordPress release so it tracks the code rather than a snapshot of it.