I think that I know why you are confused. The reason is as explained in this post - What am I doing wrong here?
The bottom line is that in order to get inventory items, sales invoices, delivery notes etc to work properly ie consistently I have to put the product manufacturer in the first column (your code column) and I put the product code in the second column (your name column) and I put the description in your description column. As explained in my other topic, if I put the code in the code column then the workflow fails.
So technically you are correct. The code column does show on the purchase order but I cannot use that column for the part code because then I cannot see manufacturer and model details so I have been using the code column for the name of laptop etc. So in essence I am without the part code.