# Get XZ curve index of an envelope

> Supported in: Batch, Streaming

Encodes the envelope in an XZ curve.

**Expression categories:** Geospatial

## Declared arguments

* **Curve preset:** Specifies the curve preset to use, higher resolution curves are more expensive to query but produce fewer false positives.<br>*Enum\<LonLat10km, LonLat150km, LonLat1km>*
* **Envelope:** Geometry envelope to index with longitude mapped to x, and latitude mapped to y.<br>*Expression\<LatLonBoundingBox>*

**Output type:** *Long*

## Examples

### Example 1: Base case

**Argument values:**

* **Curve preset:** `LON_LAT_10KM`
* **Envelope:** `envelope`

| envelope | **Output** |
| ----- | ----- |
| {<br> maxLat -> 2.0,<br> maxLon -> 3.0,<br> minLat -> 0.0,<br> minLon -> 1.0,<br>} | 16777222 |
| {<br> maxLat -> 2.0,<br> maxLon -> 3.0,<br> minLat -> *null*,<br> minLon -> 1.0,<br>} | *null* |

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