What is item change functionality ? Not required

Suggestions:
System provides a user interface functionality in which data gets auto populated on entry or selection of a field. Auto-populating form fields is a useful way to save users’ time in filling forms, An auto-populate field is a field that self-populates. Users don’t have to fill in every field of the form. System sets data from masters or from setups. Usually any code entered in the transaction screen populated the details linked to that code.
Some of the examples of item change functionality in the systems are as follows:
1)System sets up the date field on a transaction to default to the server date and time so that users do not need to use a date picker.
2) Voucher number if selected or entered then all the details of the voucher gets populated in payment details.
3) Sundry details along with tax/location details get populated on sundry code selection in any header screen.
4) Rates get populated when we select the item code in the item details screen of Purchase /Sales order.