No, there’s no missing lecture as in I haven’t recorded one yet on the treatment of revaluation decreases
It’s easy enough … remember the entries for a revaluation increase? Then reverse those entries for a subsequent revaluation decrease.
But the extent of the reversal as it’s deducted from the revaluation reserve account is limited to the extent of the amount in that account that relates specifically to that asset that is now subject to a subsequent revaluation decrease