wp-includes/rest-api/endpoints/class-wp-rest-attachments-controller.php:2597Returns the image size names which name a single file rather than a sub-size.
string[] private static function get_special_image_sizes(): array { return array( 'original', 'scaled', // Source-format original (e.g. the HEIC kept alongside its JPEG derivative). self::IMAGE_SIZE_SOURCE_ORIGINAL, // Converted-video companions for an animated GIF (the MP4/WebM and its poster). 'animated_video', 'animated_video_poster', ); }Introduced in 7.1.0.
Signature, return type and hooks compared across 1 parsed release.
src/wp-includes/rest-api/endpoints/class-wp-rest-attachments-controller.php, and regenerated for each WordPress release so it tracks the code rather than a snapshot of it.