Php/docs/exif.constants
From Get docs
Predefined Constants
The constants below are defined by this extension, and will only be available when the extension has either been compiled into PHP or dynamically loaded at runtime.
EXIF_USE_MBSTRING(int)- This constant has a value of
1if the mbstring is enabled, otherwise it has a value of0.
The exif_imagetype() lists several related built-in constants.
