Custom Auto Increment field in Umbraco
===

I have worked with my self programmed CMS but new on Umbraco. I am working on **Umbraco 4.7** with .net framework 4 and want to create a content structure somewhat like this

<pre>
MaleModels
|--------------Model (Can be multiple)
                 |----------- Model Id <strong>(Problem)</strong> 
                 |----------- Name
                 |----------- DOB
                 |----------- etc...
</pre>

I need to create node for each Model and want to assign a unique Model Id to each model but can't find any data type that can be used for Auto Increment field (As I do when programming custom .net code with SQL). I know that I can use @pageId, but I want Model Id to start from 100 and with single increment for each Model only.

Need Help...
