WAEC Financial Accounting 2013 Theory question 101

(a) Imprest system: the petty cashier is given a fixed float; at the end of each period he is reimbursed exactly what he spent, so the float is restored to the same amount.
(b) Petty cash book: a book of original entry (also a ledger account) used to record small cash payments, usually with analysis columns for each type of expense.
(c) Memorandum entries: records kept for information only that are not part of the double entry, e.g. discount columns in the cash book or a control account kept outside the ledger.
(d) Three-column cash book: a cash book with discount, cash and bank columns on both the debit and credit sides.
(e) Journal proper (general journal): book of original entry for transactions not recorded in any other subsidiary book, e.g. opening entries, correction of errors, purchase/sale of fixed assets on credit, transfers.

One clear sentence of meaning for each term is enough.