Epoch
An epoch is a period of time during which a fixed set of validators performs consensus. The Radix protocol selects the set of Top 100 validators at the start of each epoch depending how much stake has been delegated to each.
Each epoch consists of 10,000 rounds (also known as views) and the length of time of the epoch is determined by the rate at which these rounds can be produced by the validator nodes on the network.
Round / View
The terms round and view are used interchangeably and consist of 1 or more state changes that are written to the ledger. These state changes are called transactions and may consist of internal system transactions (eg. record how many proposals a validator has completed/missed) as well as user generated transaction (eg. transfer XRD, stake/unstake, create a token).
Version
TODO: A monotonically increasing number
Timestamp:
TODO: The transaction timestamp is the median of all timestamps provided by the validators when they verified a transaction (proof?). This means that it cannot be absolutely guaranteed that the timestamp always increases for each view (unlike the version which is guaranteed to increase with every round).