# `MlFillMaskInferenceOptions` [interface-MlFillMaskInferenceOptions]

| Name | Type | Description |
| - | - | - |
| `mask_token` | string | The string/token which will be removed from incoming documents and replaced with the inference prediction(s). In a response, this field contains the mask token for the specified model/tokenizer. Each model and tokenizer has a predefined mask token which cannot be changed. Thus, it is recommended not to set this value in requests. However, if this field is present in a request, its value must match the predefined value for that model/tokenizer, otherwise the request will fail. |
| `num_top_classes` | [integer](./integer.md) | Specifies the number of top class predictions to return. Defaults to 0. |
| `results_field` | string | The field that is added to incoming documents to contain the inference prediction. Defaults to predicted_value. |
| `tokenization` | [MlTokenizationConfigContainer](./MlTokenizationConfigContainer.md) | The tokenization options to update when inferring |
| `vocabulary` | [MlVocabulary](./MlVocabulary.md) |   |