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.
| constant | value | description |
|---|---|---|
| U_INVALID_STOP | 0 | stop at first invalid character |
| U_INVALID_SKIP | 1 | skip invalid characters |
| U_INVALID_SUBSTITUTE | 2 | replace invalid characters |
| U_INVALID_ESCAPE | 3 | escape invalid characters |