The Accounts Receivable Subsidiary Ledger will be a separate ledger from a company’s General Ledger, where all of the information pertaining to all Accounts Receivable will be reported.
Receivables may have only a line-item on the General Ledger of a company, but may have an entire department dedicated to servicing the receivable accounts. Because there may be a large amount of information in just the Receivables sub-account, there is often a Subsidiary Ledger dedicated to the minutia of all the Accounts Receivable business.
This may appear in company financial reports on a separate pages from the General Ledger. The ending balance of this subsidiary ledger is what appears on the line-item in the General Ledger. This is sometimes called the Control Account, which is just documented periodically with updates of the ending balance of the sub-account.
If a company finances customer purchases, or bills them for dues and so forth, the Receivables department and sub-ledger will have plenty of information to report.