Set of books are now called ledgers.A central workbench called Accounting Setup Manager is available in R12.
R12 allows you to map LE to an entire ledger or balancing segment values within a ledger.
Set of books in 11i was defined by 3 Cs,in R12,the ledger is defined by additional C;the sub-ledger accounting convention.In 11i sub-ledger accounting convention was defined at OU level.To access more than one ledger using a single responsibility given that all those ledgers share the same Calendar and Chart of account .(MRC) and journal translations have been placed under broader concept called reporting currency.The new feature of secondary ledger.New security feature called'Access Set'and there is no need to install (ADI) as a desktop client software any more are some of the new features of R12.