OptionalacceptAccepted MIME/extensions requested by the current UI, for example image/*.
Effective upload config after merging boot config and one-off overrides.
OptionalkindUpload UI kind, for example canvas-upload or media-input.
OptionalmodeMedia input mode when the upload comes from an input field.
OptionalmultipleWhether the current upload field accepts several files/media items.
OptionalsourceUpload caller, for example canvas, remote-image, or media-input.
Context passed to a custom media picker.