anchor.diff:  (defgeneric list-transactions (log after-version)
     (:documentation "List of all transactions in the log
   having version > AFTER-VERSION. The transactions
  -are odered ascendingly by version."))
  +are odered ascendingly by version.
  +
  +For transaction log to be consistent, all transactions
  +between MIN-TRANSACTION-VERSION and MAX-TRANSACTION-VERSION
  +must present in the log, there should not be gaps
  +in the transaction chain."))
   
   ;; Transaction log provides the following two functions
   ;; for commiting transactions. Two functions allow transaction
  
positive.code: there is no saved snapshots."))
  
  (defgeneric save-snapshot (log versioned-data))
  
  ;;; play transaction log
  
  
negative.code: stored in the transaction log.
  
   >= 1
   >= MIN-TRANSACTION-VERSION (if both are not absent)
  
  
  Absense of transactions in the log is handled according
  to IF-ABSENT the same way as described for MIN-TRANSACTION-VERSION."))
  