is_protected_meta()

Function: Determine whether a meta key is protected.

Source: wp-includes/meta.php:930

sanitize_meta()

Function: Sanitize meta value.

Source: wp-includes/meta.php:958

Function: Sanitize a mime type

Source: wp-includes/formatting.php:4849

Filter Hook: Filters a mime type following sanitization.

Source: wp-includes/formatting.php:4859

Function: Send a HTTP header to limit rendering of pages to same origin iframes.

Source: wp-includes/functions.php:5208