---
title: "Customizing the VTID Parameter (VDM)"
slug: "customizing-the-vtid-parameter-vdm"
updated: 2020-05-06T15:59:44Z
published: 2020-05-06T15:59:44Z
---

> ## Documentation Index
> Fetch the complete documentation index at: https://onpremises.webtrends.help/llms.txt
> Use this file to discover all available pages before exploring further.

# Customizing the VTID Parameter (VDM)

## Customizing the vtid parameter

The vtid config parameter sets a custom vtid for this user. vtid is used by Visitor Data Mart to identify visitors and by default the vtid parameter is provided by the tag's call to `wtid.js` (if `disablecookies=false`) or is a randomly generated ID (if `disablecookies=true`).

If the current site has the ablity to identify users and you wish to reuse that ID for segmenting users in Visitor Data Mart, then you can pass that custom id to the JavaScript tag using the `vtid` config parameter.

**Default Value:** undefined

**JavaScript Example:**

```
window.webtrendsAsyncInit = function () {
        var dcs = new Webtrends.dcs();
        dcs.init( {
                dcsid: "dcs9x99xxxx9xxx9xx9xxxx9x_9x9x",
                vtid: window['mysite_uid']
        });
        dcs.track();
}
```