Check boxes

Hi I was wondering if there was a way to create a check box list within a checkbox list... For example, I would have a main category and then sub categories:

 Dogs (main)

(sub)



Poodle

Dalmation

German shepherd

Bull dog
I would like to be able to check the main category as well as any option located in the sub category.   Is there a simple way to do this?

Thanks,

Jen

 
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