Item tracking

Hi NAV Experts,
I am new to NAV. And I am working on Item re-classification. (Generally moving some items to another location.)
When I click on item Tracking Lines and on the Item tracking Page I see the Serial number and lot number.
On Assist of Serial number, I am able to view the available serial numbers and the Lot number which I need to move.
I understand we have the table called "Serial No. Information" and "Lot No. Information" where the Quantity on hand shows the availability.

Question :
When the Item tracking page is open, And select any Serial number from the availability and assigns the Quantity. I see the source table of the page is tracking Specification, But the data is not populated to the table.
Need to know the logic behind selection of Serial numbers and its assignments.
Thanks !