<sub>Please forgive the newbie question!</sub>

In an REST API URL Parameter string, how do I *exclude* records based on the presence of a certain field (like the equivalent of SQL's `[fieldname] Is Null`)?
 
**Example**:

 - Results for **Closed** questions include field **`closed_date=1234567890`**.

 - Results for **Open** questions do not include this field as a *`Null`* as I would expect.

Is there a parameter I can add to the URL to **exclude questions that *have* the field**?


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The only information I could find was from the documentation:

>**Absent Fields**
>
><sub>To save space, the API does not return null values, instead opting to exclude the field altogether in the returned JSON. Fields that are not always guaranteed to be set (closed_date on question objects for example) are indicated in the per-type documentation.  ([**Source**][1])</sub>



  [1]: https://api.stackexchange.com/docs/absent-fields