Resource Types
Summaries of supported encodings
Multibyte String
PHP Manual

# 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.

`MB_OVERLOAD_MAIL` (integer)
`MB_OVERLOAD_STRING` (integer)
`MB_OVERLOAD_REGEX` (integer)
`MB_CASE_UPPER` (integer)
`MB_CASE_LOWER` (integer)
`MB_CASE_TITLE` (integer)

Resource Types
Summaries of supported encodings
Multibyte String
PHP Manual