# Fields

You can specify what fields to read from your S3 file through the fields table.

* Click **Get Fields** to have the step populate the table with fields derived from the source file based on the current specified settings (such as **Delimiter** or **Enclosure**). All fields identified by this step will be added to the table.
* Click **Preview** to view the data coming from the source file.

The table contains the following columns:

| Column        | Description                                                                                                                                                                                                                                                                                                                                                             |
| ------------- | ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| **Name**      | Specify the name of the field.                                                                                                                                                                                                                                                                                                                                          |
| **Type**      | Select the field’s data type from the dropdown list or enter it manually.                                                                                                                                                                                                                                                                                               |
| **Format**    | Select the format mask (number type) from the dropdown list or enter it manually. See [Common Formats](https://docs.pentaho.com/pdia-data-integration/10.2-data-integration/pdi-transformation-steps-reference-overview/common-formats) for information on common valid date and numeric formats you can use in this step.                                              |
| **Length**    | <p>Specify the length of the field, according to the following field types:- <strong>Number</strong></p><p>Total number of significant figures in a number</p><ul><li><strong>String</strong></li></ul><p>Total length of the string</p><ul><li><strong>Date</strong></li></ul><p>Length of printed output of the string (for example, four is a length for a year)</p> |
| **Precision** | Specify the number of floating point digits for number-type fields.                                                                                                                                                                                                                                                                                                     |
| **Currency**  | Specify the symbol used to represent currencies. For example: `$` or `€`                                                                                                                                                                                                                                                                                                |
| **Decimal**   | Specify the symbol used to represent a decimal point, either a period "`.`" or a comma "`,`".For example: `5,000.00` or `5.000,00`                                                                                                                                                                                                                                      |
| **Group**     | Specify the method used to separate units of thousands in number of four digits or larger, either a period “`.`” Or a comma “`,`”. For example: `5,000.00` or `5.000,00`                                                                                                                                                                                                |
| **Trim type** | Select the trimming method (**none**, **left**, **right**, **both**) to apply to a string, which truncates the field before processing. Trimming only works when no field length is specified.                                                                                                                                                                          |

See \[Understanding PDI data types and field metadata]\(../../../../Data%20Integration%20Perspective/Data%20Integration%20perspective%20in%20the%20PDI%20client/Advanced%20topics%20(PDI%20perspective)/Understanding%20PDI%20data%20types%20and%20field%20metadata.md) to maximize the efficiency of your transformation and job results.