Fix #986 and improve documentation.
Fix #986 and improve documentation.

paulbdavis/ledger,afh/ledger,jwakely/ledger,duncanmortimer/ledger,afh/ledger,paulbdavis/ledger,paulbdavis/ledger,duncanmortimer/ledger,paulbdavis/ledger,duncanmortimer/ledger,ledger/ledger,afh/ledger,paulbdavis/ledger,ledger/ledger,afh/ledger,paulbdavis/ledger,duncanmortimer/ledger,jwakely/ledger,ledger/ledger,duncanmortimer/ledger,jwakely/ledger,ledger/ledger,ledger/ledger,duncanmortimer/ledger,jwakely/ledger,jwakely/ledger,duncanmortimer/ledger,jwakely/ledger,afh/ledger,jwakely/ledger,paulbdavis/ledger