What's the difference between `transaction and `transaction`event in VHDL

Question

I understand that event is when the signal *transitions* to/from a value. transaction is when a signal is assigned a value, even if the value is the same as the previous value.

My question is what is transactionevent? Does it mean that -both- a transaction and an event has taken place on a signal or does it mean that either a transaction has taken place OR an event has taken place on the given signal. Is it an AND of transaction and event or is it an OR?

Thanks.

Answer 1

The 'transaction attribute is a signal of type bit that toggles on every assignment to a signal. Hence, because every signal can create a 'event, 'transaction'event simply occurs on every transaction, or signal assignment.

'event is a function that returns a boolean when signal has changed value.