Order unit in Info record

Hi all,

I have an info record for a material xyz from vendor abc. The order unit for the same was NOS and now i changed it to EA. 1 EA = 1 NOS. Basic unit of measure in master record is NOS.

1) When i click on the conditions tab, the system says that this function is no longer possible after the order unit has been changed.

2) During creation of a PO for the material xyz and the vendor abc, my understanding is that only EA order unit should be accepted and not NOS. But system by default is taking NOS and does not throw any error on not changing the order unit.

Kindly help me understand this.

Regards

Madhu