---
title: "Defining preflight rules | Customer's Canvas On-Premises"
canonical: "https://customerscanvas.com/docs/on-premises/preflight/howto/define-preflight-rules/"
---

# Defining preflight rules

> To enable a preflight check, you need to define the [config.rules](https://customerscanvas.com/docs/on-premises/preflight/reference/config.md#preflight-rules) array. This array contains as many elements as the [rules](https://customerscanvas.com/docs/on-premises/preflight/reference/rules.md) that must be checked.

## How to set up preflight rules

For example, you may want to adjust the color space and resolution of products. In this case, you must define two elements in the [rules](https://customerscanvas.com/docs/on-premises/preflight/reference/rules.md) array.

```json
{
    "widgets": [{
        "name": "preflight",
        "type": "preflight",
        "params": {
            "config": {
                "rules": [
                    {
                        "type": "colorspace",
                        "severity": "error",
                        "enableFix": true,
                        "params": {
                            "allowedColorSpaces": ["CMYK"]
                        }
                    },
                    {
                        "type": "resolution",
                        "severity": "warning",
                        "params": {
                            "target": 300
                        }
                    }
                ]
            }
        }
    }]
}
```

Here, severity specifies whether a preflight problem can remain in the print file or if it must be fixed.

As a result, if user files contain graphics in color spaces other from CMYK, then the Preflight Tool considers them invalid and enables the Fix button to resolve this issue automatically. If these files have a resolution of less than 300 DPI, then a warning only appears in the editor.

## How to specify spot colors

You can define a set of allowed spot colors in a rule of the spotcolors type. In the [allowed](https://customerscanvas.com/docs/on-premises/preflight/reference/rules.md#spot-colors) object, you can list spot color names and use regular expressions. Other spot colors will be considered invalid, and the Preflight Tool will suggest to replace them.

```json
{
    "widgets": [{
        "name": "preflight",
        "type": "preflight",
        "params": {
            "config": {
                "rules": [{
                    "type": "spotcolors",
                    "severity": "error",
                    "params": {
                        "allowed": {
                            "names": [ "PANTONE 653 C", "PANTONE 649 C", "PANTONE 7677 C" ]
                        }
                    }
                }]
            }
        }
    }]
}
```

## How to define rules for certain pages

You can configure preflight rules so that they apply to [certain pages](https://customerscanvas.com/docs/on-premises/preflight/reference/config.md#preflight-rules). For example, to apply a rule to all even pages:

```json
{
    "widgets": [{
        "name": "preflight",
        "type": "preflight",
        "params": {
            "config": {
                "rules": [
                    {
                        "type": "colorspace",
                        "severity": "error",
                        "enableFix": true,
                        "pages": ["/2"],
                        "params": {
                            "allowedColorSpaces": ["CMYK"]
                        }
                    }
                ]
            }
        }
    }]
}
```

Here, we have defined `pages` as an array of strings with the element `"/2"`, which applies the rule to every second page. To apply the rule to every third page, pass `"/3"`, and so on.

You can also list page numbers in the `pages` array to apply rules to the corresponding pages. For example, to apply them to the second and fourth pages:

```json
    ...
    "pages": [2, 4],
    ...
```

## How to configure the Fix All button

You may want to configure a single button to fix several or even all preflight problems in one click. Let's see how you can configure the **Fix All** button to resolve errors and warnings from the rules with the `enableFix` property set to `true`.

```json
{
    ...
    "interface": {
        "customButtons": [
            {
                "title": "Fix All",
                "filter": {
                    "severity": ["error", "warning"]
                }
            }
        ]
    }
}
```

Here, we only specified the `severity` of the rules. Instead, you can list the required rules in the [filter.types](https://customerscanvas.com/docs/on-premises/preflight/reference/config.md#the-user-interface) array.

The Preflight Tool also allows you to change the button appearance. For details, you can refer to [Custom Buttons](https://customerscanvas.com/docs/on-premises/preflight/configure-ui.md#custom-buttons).