---
updatedAt: 2026-10-15T13:52:08.000Z
agentTools:
  projectIndex: https://docs.pebblestream.com/llms.txt
---

# leftmost-column

Marks a column that receives a **constant**: the index of the first (leftmost) column of the record's _block_ inside the template worksheet.

`pebblestream:leftmost-column`

Together with [`rightmost-column`](rightmost-column.md), [`top-row`](top-row.md)
and [`bottom-row`](bottom-row.md) it describes the bounding rectangle of the table
the record was extracted from — handy when the pebble needs to know (or later
rewrite) where in the user's template the data came from.

## Syntax

```
pebblestream:leftmost-column
```

* No arguments.
* Placed on the **header cell of the column** that should hold the constant.
* Requires [`template-name`](template-name.md) on the same worksheet.

## Example

| column | header        | comment                                 |
| ------ | ------------- | --------------------------------------- |
| A      | `Block left`  | `pebblestream:leftmost-column`          |
| B      | `Block right` | `pebblestream:rightmost-column`         |
| C      | `Item`        | `pebblestream:template-name:"Partners"` |

Every record extracted from a block starting at column `B` of the template gets
that column index in `Block left`.

## Errors

| Error                                 | Cause                             |
| ------------------------------------- | --------------------------------- |
| `dir-too-many-args`                   | Arguments were supplied.          |
| `missing-the-template-name-directive` | The sheet has no `template-name`. |

## Related

* [Template directives](template-directives.md) — how extraction works
* [block-id](block-id.md) — which block the record came from
* [block-row-count](block-row-count.md) — height of the block