Why is there a PGN SetUp tag?

[niklasf]

To start a game with a non-standard position there is a FEN tag. The PGN specification says it must be accompanied by a SetUp tag.

I am trying to understand this design decision. Is there any hidden reason why a simple FEN tag should not be sufficient?

Best,
Niklas

[Ferdy]

To start a game with a non-standard position there is a FEN tag. The PGN specification says it must be accompanied by a SetUp tag.

I am trying to understand this design decision. Is there any hidden reason why a simple FEN tag should not be sufficient?

Best,
Niklas

The setup tag may take two values 0 or 1. If the starting position of the game is the starting standard position and is shown in the fen tag the setup tag should have a value of 0.
If the game starts from position other than the standard starting position, the fen tag and setup tag should be indicated in the game tag pair section. The setup tag should have a value of 1 in this case.
When the game starts from standard starting position, the fen and setup tag pairs may not be shown in that section.

[sje]

The SetUp tag should have been left out of the specification. The FEN tag is sufficient to indicate an arbitrary starting position.