Q: timeStamp of Transaction

Hi there
Puzzled about the timeStamp of Transaction:
It said: The number of seconds elapsed since the creation of the nemesis block.

Does this means the creation of each block in the block chain?
By this case, it is possible that Transaction A is later than Transaction B, but Transaction A have a smaller timeStamp than TransactionB?

Or it is the time of the Nem block chain creation?
If it is this case, when is the creation time?

Nemesis block is the first one (as far as I know) - it’s time is 0. All other blocks timestamp are counted from this block. When you want calculate real time of creation you must add timestamp and nemesis block timestamp when creation has taken place (it was somewhere in 2015). All wallets and blockchain explorers do this for you.