How could 2d array be defined directly at the equation window in Microwave Office 7?

[Vadim]

Hello,

I have a question about mathematic equation at the Microwave Office v.7.
How could be 2d array defined directly at the equation window?

For example 1D vector is simply to defined as vec={1,2,3,4,5} or vec={"a","b","c","d"} and for this definition vec[1]: 1 (a)

But I would like to define 2D array, and arr={{1,2,3},{4,5,6}} is incorrect.
Please whar is correct form for 2D array?
Do you have some experience?

thanks