: str_replace(): Passing null to parameter #2 ($replace) of type array|string is deprecated in
* Interface with constants for the different types of attributes.
* phpcs:disable Generic.Files.LineLength.TooLong
* @package ampproject/amp-toolbox
const AMP4ADS = 'amp4ads';
const AMP4ADS_BOILERPLATE = 'amp4ads-boilerplate';
const AMP4ADS_EMOJI = self::AMP_EMOJI . '4ads';
const AMP4ADS_EMOJI_ALT = self::AMP_EMOJI_ALT . '4ads';
const AMP4EMAIL = 'amp4email';
const AMP4EMAIL_BOILERPLATE = 'amp4email-boilerplate';
const AMP4EMAIL_EMOJI = self::AMP_EMOJI . '4email';
const AMP4EMAIL_EMOJI_ALT = self::AMP_EMOJI_ALT . '4email';
const AMP_BOILERPLATE = 'amp-boilerplate';
const AMP_CUSTOM = 'amp-custom';
const AMP_EMOJI = "\xE2\x9A\xA1";
const AMP_EMOJI_ALT = "\xE2\x9A\xA1\xEF\xB8\x8F"; // See https://github.com/ampproject/amphtml/issues/25990.
const AMP_ONERROR = 'amp-onerror';
const AMP_RUNTIME = 'amp-runtime';
const AMP_SCRIPT_SRC = 'amp-script-src';
const ARIA_HIDDEN = 'aria-hidden';
const ARIA_LABEL = 'aria-label';
const AS_ = 'as'; // Underscore needed because 'as' is a PHP keyword.
const ATTRIBUTION = 'attribution';
const AUTOPLAY = 'autoplay';
const CHARSET = 'charset';
const CLASS_ = 'class'; // Underscore needed because 'class' is a PHP keyword.
const CONTENT = 'content';
const CROSSORIGIN = 'crossorigin';
const CUSTOM_ELEMENT = 'custom-element';
const CUSTOM_TEMPLATE = 'custom-template';
const DECODING = 'decoding';
const DISABLE_INLINE_WIDTH = 'disable-inline-width';
const HEIGHTS = 'heights';
const HOST_SERVICE = 'host-service';
const HTTP_EQUIV = 'http-equiv';
const I_AMPHTML_BINDING = 'i-amphtml-binding';
const I_AMPHTML_NO_BOILERPLATE = 'i-amphtml-no-boilerplate';
const I_AMPHTML_SSR = 'i-amphtml-ssr';
const I_AMPHTML_VERSION = 'i-amphtml-version';
const IMAGESRCSET = 'imagesrcset';
const IMAGESIZES = 'imagesizes';
const IMPORTANCE = 'importance';
const INTRINSICSIZE = 'intrinsicsize';
const LIGHTBOX = 'lightbox';
const LOADING = 'loading';
const NOLOADING = 'noloading';
const NOMODULE = 'nomodule';
const OBJECT_FIT = 'object-fit';
const OBJECT_POSITION = 'object-position';
const PLACEHOLDER = 'placeholder';
const PROFILE = 'profile';
const REFERRERPOLICY = 'referrerpolicy';
const TABINDEX = 'tabindex';
const TEMPLATE = 'template';
const VIEWPORT = 'viewport';
const ALL_AMP = [self::AMP, self::AMP_EMOJI, self::AMP_EMOJI_ALT];
const ALL_AMP4ADS = [self::AMP4ADS, self::AMP4ADS_EMOJI, self::AMP4ADS_EMOJI_ALT];
const ALL_AMP4EMAIL = [self::AMP4EMAIL, self::AMP4EMAIL_EMOJI, self::AMP4EMAIL_EMOJI_ALT];
const ALL_BOILERPLATES = [self::AMP_BOILERPLATE, self::AMP4ADS_BOILERPLATE, self::AMP4EMAIL_BOILERPLATE];
const TYPE_HTML = 'text/html';
const TYPE_JSON = 'application/json';
const TYPE_LD_JSON = 'application/ld+json';
const TYPE_PDF = 'application/pdf';
const TYPE_MODULE = 'module';
const TYPE_TEXT_PLAIN = 'text/plain';
const REL_AMPHTML = 'amphtml';
const REL_CANONICAL = 'canonical';
const REL_DNS_PREFETCH = 'dns-prefetch';
const REL_MODULEPRELOAD = 'modulepreload';
const REL_NOAMPHTML = 'noamphtml';
const REL_NOFOLLOW = 'nofollow';
const REL_PRECONNECT = 'preconnect';
const REL_PREFETCH = 'prefetch';
const REL_PRELOAD = 'preload';
const REL_PRERENDER = 'prerender';
const REL_STYLESHEET = 'stylesheet';
const DATA_AMP_STORY_PLAYER_POSTER_IMG = 'data-amp-story-player-poster-img';
const DATA_HERO = 'data-hero';
const DATA_HERO_CANDIDATE = 'data-hero-candidate';
const CROSSORIGIN_ANONYMOUS = 'anonymous';