What is the meaning of entries to apportion recorded cost?

What is the meaning of entries to apportion recorded cost?
Apportioning cost means dividing cost betweenExpired cost (depreciated value) and Unexpired cost (notdepreciated yet). Cost which is used or whose time period isover is expired cost which can also be called as expense now, whileunexpired cost can be named as remaining book value. For example,Prepaid rent was paid in September for the coming 4 months was$4000. Now, at the end of September the expired cost will be $1000(and will be recorded in income statement as expense) and Unexpiredcost will be $3000 (& will be recorded in Balance sheet as anasset ). Entry at the start of September would be
Prepaid Rent a/c $4000 (Dr)
Cash a/c $4000 (Cr)Entry at the end of September would beRent a/c $1000 (Dr)
Prepaid Rent a/c $1000 (Cr)
See here, the used up cost or you may say asset has been turnedinto an expense, mitigating the value of Prepaid rent with$1000. Suppose you are preparing Balance Bheet atthe end of September, the $1000 will be recorded in IncomeStatement as an expense while the Remaining $3000 will berecorded as current asset in Balance Sheet.