how to get blanket column from sales order matrix

Hi,

I need to know the index of column "Is Blanket" in sales order matrix.

Generally, is there a way to get all columns index for a matrix?

currently i'm using:

colBlk = mSales.get_Columns().Item("U_blanket");

but it doesn't work, i got the error "Invalid column".

Can anyone help me?

Thank's in advance.

Best Regards

Andrea