> ## Documentation Index
> Fetch the complete documentation index at: https://docs.blnkfinance.com/llms.txt
> Use this file to discover all available pages before exploring further.
# Create matching rule
> Create a matching rule for reconciliation.
export const CtaCallout = props => {
const {title, buttonLabel, href, trackingEvent, buttonTarget, rel = "noopener noreferrer", children} = props;
const handleCtaClick = () => {
if (typeof window === "undefined" || !trackingEvent) {
return;
}
try {
window.dispatchEvent(new CustomEvent("blnk:docs-cta", {
detail: {
name: trackingEvent,
href
}
}));
} catch {}
try {
window.posthog?.capture?.(trackingEvent, {
href
});
} catch {}
const gaPayload = {
cta_href: href
};
try {
window.gtag?.("event", trackingEvent, gaPayload);
} catch {}
try {
window.dataLayer = window.dataLayer || [];
window.dataLayer.push({
event: trackingEvent,
...gaPayload
});
} catch {}
};
const isExternal = typeof href === "string" && (/^https?:\/\//i).test(href);
const target = buttonTarget ?? (isExternal ? "_blank" : undefined);
const linkRel = isExternal ? rel : undefined;
return ;
};
If you're using the auto-provisioned `Enterprise Core` instance included with your Production License deployment, set the base URL to: `https://ENTERPRISE_PUBLIC_URL/core`.
If you're connecting to a different Core instance, use the publicly accessible base URL for that instance instead.
### Authorization
If set, the API uses an API key for authentication. Include the following header in your requests: `X-blnk-key: `.
Replace `` with your secret API key. Ensure the key is kept secure and not exposed in public repositories or client-side code.
See also: [Scoped API keys](/api-keys/overview) and [Secure your Blnk server](/advanced/secure-blnk).
### Body
Name of the matching rule.
A brief description of what the matching rule does.
An array of criteria that defines the rule. Each criteria is defined by 3 attributes - `field`, `operator`, `allowable_drift`.
Fields to match. It can be `"amount"`, `"currency"`, `"reference"`, `"description"`, or `"date"`.
Defines how the selected field should be compared with internal records. Depending on the field, this can be `"equals"` or `"contains"`.
* `equals`: The field in the external record must exactly match the corresponding field in your Blnk Ledger.
* `contains`: Parts of the external field's value must be found in your Blnk Ledger.
Helps to accomodate small variations in transaction amounts between both records. Only applicable to amount and date fields.
* Amount drift: Measured in percentages, e.g., 1% is `"allowable_drift": 0.01`
* Date drift: Measured in seconds, e.g., 1 hour is `"allowable_drift": 3600`
For further details, refer to: [Handling discrepancies with drifts](/reconciliations/matching-rules#handling-discrepancies-with-drifts)
```json theme={"system"}
{
"name": "Default matcher",
"description": "Amount with 1% drift matcher",
"criteria": [
{
"field": "amount",
"operator": "equals",
"allowable_drift": 0.01
},
{
"field": "currency",
"operator": "equals"
},
{
"field": "date",
"operator": "equals",
"allowable_drift": 1800
},
{
"field": "reference",
"operator": "contains"
}
]
}
```
```json 400 theme={"system"}
{
"error": "invalid operator",
"error_detail": {
"code": "RECON_RULE_INVALID",
"message": "invalid operator"
}
}
```
## Need help?
We are very happy to help you make the most of Blnk, regardless of whether it is your first time or you are switching from another tool.
To ask questions or discuss issues, please [contact us](mailto:support@blnkfinance.com) or [join our Discord community](https://discord.gg/7WNv94zPpx).
Sign up and manage your ledger with our back-office dashboard. You can invite teammates to collaborate and manage your ledger operations directly from the dashboard.