What is the use of Reference 1, 2 Fields in the AP Invoice Lines? and How to use the same?

 Hi,

We need to to attach a particular information for each AP Invoice line.  We are planning to create a LOV from which user will have to select one for each line.

Our concern is that if we assign this information in a DFF at invoice line level then for an invoice having more than 100 lines user will have to select such value individually.

That is why we need to explore the option of reference 1 and reference 2  filed which we see are not capturing any data currently and hence we please let us know when these fields are use at all. And from where do we enter values for this field.