Slot Types

A slot is an attribute of a specific intent. A slot is specified by two attributes: type and name. For example, the slots associated to the searchWeatherForecast intent would be:

  • The weather_forecast_locality slot has a default type and the assistant will simply learn about it from your queries.

  • The weather_forecast_start_datetime slot has a built-in type snips/datetime which means that the assistant uses a pre-trained detection algorithm.

Three types of slots can be handled by the NLU engine: custom, default and built-in slot types.

Custom slot type

Custom slot type allows you to define your own slot type. Custom slot types are meant for two major use cases:

  1. You want to manually specify all the values for a given slot type, and specify synonyms.

  2. You plan to reuse a certain slot type between several custom intents. Let’s assume you want to build an assistant for a restaurant. You may want to create intents such as createOrder, cancelOrder, etc. All these intents may share an ordered_dish slot type. Defining a common custom slot type for ordered_dish allows you to extend its value list with all the values found in the intents that include this slot type.

If you want to learn more about how to create a custom slot type, go to this tutorial for more details.

We're also providing a powerful feature called entity extension that will allow you to automatically enrich your custom slot type with hundreds of values via our Wikidata powered tool. This feature allows you to save a great amount of time, and will prevent you from doing the cumbersome work of writing / thinking of all the possible values for a given slot type.

Default slot type

By default, a new slot has the default slot type. This default slot type does not allow you to specify values and synonyms for the slot, aside from the values that are defined in the examples of queries provided for the intent. If you want to extend the list of values for a slot, please consider creating a custom slot type.

Built-in slot type

The built-in slot type can be used by everyone out of the box. It is strongly advised to use them when specifying your intent's slots whenever possible. They come with powerful built-in entity detectors that have been specifically trained to detect these types.

Let's assume you're building an intent such as bookRestaurant with slots party_size, and reservation_datetime. You would specify slot types for both of these slots as being built-in ones:

  • party_size: snips/number

  • reservation_datetime: snips/datetime

The following built-in slot types are available depending on the language:

  • Numeric entities:number,ordinal,amountOfMoney, percentage, temperature

  • Time related entities: datetime, duration

  • Music entities: musicArtist, musicAlbum, musicTrack

You will find below a detailed table for each type of entity with related built-in slot type categories, supported languages, units and ranges, possible values and serialization examples.

Numeric entities

Supported languages




Additional information

en, fr, de, es, it, ja


Integer number, positive or negative

twenty-two minus one hundred three million seventy-five

Supported range:

-999.999.999.999 to 999.999.999.999

Serialization example

twenty-two { "kind": "Number", "value": 22.0 }

en, fr, de, es, it, ja


Ordinal number

second tenth twenty-third

  • Supported range for en, fr, de, ja: 1st to 1000th

  • Supported range for es: 1st to 20th

  • Supported range for es: 1st to 10th

Serialization example

second { "kind": "Ordinal", "value": 2 }

en, fr, de, es, it, ja


Amount of money (decimal or integer number + major currencies)

10.05€ ten dollars eight hundred twenty-two pesos

  • Supported currencies: $, USD, AUD, CAD, HKD, EUR, £, GBP, CHF, KR, DKK, NOK, SEK, RUB, INR, JPY, CNY, ¥, KRW, ฿ - For currencies that share part of the name (e.g. dollars, US dollars, Hong Kong dollars), the currency is resolved as $ if there is no more info given (dollar). Otherwise US dollars is resolved as USD

  • Supported range for en, fr, de, es, it: 0 to 999.999.999.999

  • Supported range for ja: 0 to 99.999.999 - Decimal numbers only supported in French at the moment

Serialization example

10.05€ { "kind": "AmountOfMoney", "value":10.05, "precision": "Approximate", "unit": "€" }

one dollar { "kind": "AmountOfMoney", "value": 1, "precision": "Exact", "unit": "$" }, five American dollars { "kind": "AmountOfMoney", "value": 5, "precision": "Exact", "unit": "USD" }

en, fr, de, es, it, ja



25% fifty-two percent one hundred percent

Serialization example

25% { "kind": "Percentage", "value": 25.0 }

en, fr, de, es, it, ja



70 Kelvin -3°C twenty-three degrees one hundred degrees Fahrenheit

Positive or negative expressed in degrees, Celsius, Kelvin or Fahrenheit

Serialization example

70 Kelvin { "kind": "Temperature", "value": 70.0, "unit": "kelvin"}

one degree { "kind": "Temperature", "value": 1, "unit": "degree"} minus three degrees celsius { "kind": "Temperature", "value": -3, "unit": "celsius"}

We have two kinds of entities for time: date/time and duration

Date/Time entities

These are expression of time that can be positioned in time. We have two kinds of dates times:

  1. Instant times e.g. "tomorrow at 7:30pm"

  2. Time intervals e.g. "from Monday to Wednesday"

1. Instant time

Expression of time that can be understood as a single time unit (a cycle, with a specific grain) positioned at a specific moment. Examples:

  • "now" (grain: second)

  • "tomorrow at 7:30pm" (grain: minute)

  • "around seven o'clock" (grain: hour)

  • "on the day before yesterday" (grain: day)

  • "next week" (grain: week)

  • "for January 2019" (grain: month)

  • "this quarter" (grain: quarter)

  • "in 2020" (grain: year)

Resolution in the console: kind: InstantTime, value: date + time (yyyy-mm-dd hh:mm:ss), grain: Year, Quarter, Month, Week, Day, Hour, Minute, Second; precision: “Exact”, “Approximate"

2. Time interval

Expression of time consisting of multiple successive time units, and that can be positioned in time. Time intervals can be of three kinds:

1. Has a starting point and a finishing point:

  • "from today 3 pm to tomorrow 8 am" (starting point: today 3 pm, finishing point: tomorrow 8 am)

  • "from Monday to Wednesday" (starting point: Monday, finishing point: Wednesday)

2. The starting point or the finishing point can be implicit:

  • "for the next two hours" (starting point [implicit]: now, finishing point: in 2 hours)

  • "during the last three weeks" (starting point: 3 weeks ago, finishing point [implicit]: now)

The implicit starting or finishing point is not exactly now, but some definite time near now. In "for the next two hours", the starting point is actually the beginning of the next hour, not the exact moment of enunciation.

3. The starting point or the finishing point can be undefined:

  • "until next year" (starting point: undefined, finishing point: next year)

  • "since last Friday" (starting point: last Friday, finishing point: undefined)

Resolution in the console: kind: TimeInterval, from: starting point (always included in the time interval), to: finishing point (always excluded from the time interval)

Duration entity

Expressions of time that can NOT be positioned in time. This means that starting and finishing points are not defined, neither explicitly nor implicitly. Examples:

  • "for 3 years"

  • "during two hours and five minutes"

Supported languages




Additional information

en, fr, de, es, it, ja


Time, time interval, date, date interval, or combination of date and time (or time interval)

seven am (InstantTime) at midnight (InstantTime) from five to six pm (TimeInterval) this morning (TimeInterval) on the third of July 2020 (InstantTime) next Monday (InstantTime) from yesterday until tomorrow (TimeInterval) during the next summer (TimeInterval) June 2nd at 9 pm (InstantTime) at ten in the evening on Christmas day (InstantTime) yesterday morning (TimeInterval) from yesterday to next Monday at two thirty pm (TimeInterval)

Serialization example

seven am { "kind": "InstantTime", "value": "2017-06-13 07:00:00 +02:00", "grain": "Hour", "precision": "Exact" } or from five to six pm { "kind": "TimeInterval", "from": "2017-06-07 17:00:00 +02:00", "to": "2017-06-08 18:00:00 +02:00" }

en, fr, de, es, it, ja


Time duration

3 months four seconds 8 years five hours fifteen minutes and eight seconds

Serialization example

3 months { "kind": "Duration", "years": 0, "quarters": 0, "months": 3, "weeks": 0, "days": 0, "hours": 0, "minutes": 0, "seconds": 0, "precision": "Exact" }

Music entities

Supported languages




Additional information

en, fr


Artist or band name

Radiohead Queen Madonna Björk

Serialization example

Radiohead { "kind":"MusicArtist", "value": "Radiohead" }

en, fr


Album name

Nevermind Thriller OK Computer London Calling

Serialization example

Nevermind { "kind": "MusicAlbum", "value": "Nevermind" }

en, fr


Song name

Bohemian Rhapsody Call me Respect Fake plastic trees

Serialization example

Bohemian Rhapsody { "kind": "MusicTrack", "value": "Bohemian Rhapsody" }

Required slots and dialog

In some cases, an application requires certain slots to be present for a command to be processed. This could for example be the case for a moneyTransfer intent, requiring an amount slot. Using the web console, you can choose to force the presence of a specific slot in an intent. If the assistant detects an intent but does not identify the required slot in the query, it will ask the user for the value of the slot. You can define in the console the question to ask the user when a slot is missing.