Multi-dimensional array form post via ajax

I have a form post that is occuring via ajax to a cf script.  One of the variables is a multi-dimensional array.  I can't seem to be able to get access to the values of the array.  When I do a dump on Form, I get keys that look like this:

<CFDUMP var="#FORM#" />

The result(keys):

data[var1], data[var2], data[var3]

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When I try to acess the vars though, all I get is errors:

FORM.data["var1"] .....shows an error

FORM.data.var1 ......shows an error

On the other elements that are not an array from the form post, I can access those values just fine:

FORM.var4 .....displays value

FORM.var5 ..... displays value

What am I doing wrong here?