Alternate sales unit in sales order

Hello ,

We used to maintain all the alternate sales unit in material master so that we can enter any one of them in sales order.

I have one service material for which no alternate unit is maintain in material master but in salse order F4 help gives me many sales unit which i can choose.

I would like to know that from where these alternate units are getting picked ?

I am working on ECC6.0 version.

Is there is any config for it ?

Thanks ,

Nitin