Fetching fields in quotation item table

How do i fetch a field in quotation item from item master …can anyone provide me some input. Let’s say if the field is xyz then should the code be item_code.xyz

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Well first and most important question as of now is how do i fetch a value for the field named expiry date which is present in batch doc …i want it item master to have it then from item master it should be fetched in quotation items table as well
item_code.expiry_date throws an error in quotation