wp-includes/meta.php:1286Determines whether a meta key is considered protected.
$meta_keystring$meta_typestringoptional''boolOne hook fires while is_protected_meta() runs, in this order:
Filters whether a meta key is considered protected.
function is_protected_meta( $meta_key, $meta_type = '' ) { $sanitized_key = preg_replace( "/[^\x20-\x7E\p{L}]/", '', $meta_key ); $protected = strlen( $sanitized_key ) > 0 && ( '_' === $sanitized_key[0] ); /** * Filters whether a meta key is considered protected. * * @since 3.2.0 * * @param bool $protected Whether the key is considered protected. * @param string $meta_key Metadata key. * @param string $meta_type Type of object metadata is for. Accepts 'post', 'comment', 'term', 'user', * or any other object type with an associated meta table. */ return apply_filters( 'is_protected_meta', $protected, $meta_key, $meta_type );}Introduced in 3.1.3. Unchanged from 6.7.7 through 7.1.0.
Signature, return type and hooks compared across 5 parsed releases.
src/wp-includes/meta.php, and regenerated for each WordPress release so it tracks the code rather than a snapshot of it.