user315: A question of rulebook pedantry:
Effective July 2014, the FIDE has revised its Laws of Chess.  As you know, the Laws have long allowed a player to claim a draw by repetition.  The July 2014 Laws, sect. 9.2, however append this curious sentence:

When a king or a rook is forced to move, it will lose its castling
  rights, if any, only after it is moved.

Sect. 9.2 does not explicitly link this sentence to the draw by repetition.  The sentence floats alone.
Because there seems to be no other reason for the sentence to be in sect. 9.2, one tends to read it to imply that, at game's start, four castling rights exist—White's kingside, White's queenside, Black's kingside and Black's queenside—and that these castling rights are as much features of the position as, say, a white pawn on b3 is a feature of the position.  White's kingside castling right vanishes when Rh1 or Ke1 is first moved, or when Rh1 is captured (though, actually, sect. 9.2 does not mention the rook's capture), and cannot vanish at any other time or in any other way.  Specifically, White's kingside castling right vanishes neither (a) when White is temporarily prevented from castling kingside nor (b) when no legal continuation exists in which White could castle kingside.
In other words, a castling right exists even if it can never be used; and this affects when a draw can be claimed.
Could one read sect. 9.2 in any other way?
For example, this (nonsensical but technically illustrative) game is not yet a draw:
[Title "White to open, illustrating sect. 9.2"]
[FEN "rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq - 0 1"]

1. e4 d5 2. exd5 Qxd5 3. Nc3 Qa5 4. g3 Nf6 5. Bg2 b6 6. Bxa8 Bd7 7. Qh5 Qxh5 8. Rb1 Nc6 9. b3 e6 10. Na4 Bd6 11. c3 O-O 12. Nh3 Qe5+ 13. Kf1 Qf5 14. Ke1 Qe5+ 15. Kf1 Qf5 16. Ke1 Qe5+

After 12... Qe5+, three castling rights have already vanished, but White's kingside right remains, even though no continuation exists in which White might eventually castle.  On the other hand, after 14... Qe5+ or 16... Qe5+, all four castling rights have vanished.  Therefore, triple repetition has not yet occurred.
Is my understanding correct?  Or is an alternate, reasonable interpretation possible?
Further reading:

Geurt Gijssen.  Arbiter's Notebook.
Bill Smythe.  USCF discussion.


user3890: My interpretation of the rules (which in this aspect I believe to be correct) is the same as yours. Although the example you provide with castling rights is conceptually a little more challenging, the problem is exactly the same as the one arising when the "en passant" rule is allowed on the first move:
[Title "White to open, illustrating sect. 9.2"]
[FEN "rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq - 0 1"]
[Result "1/2 - 1/2"]

1. e4 e5 2. d4 Nf6 3. d5 c5 {First time this position happens.} 4. Qf3 Ng8 5. Qd1 Nf6 {Second time this "position" happens, but now white cannot take the pawn en passant, thus making actually this the first time this position happens.} 6. Qf3 Ng8 7. Qd1 Nf6 {Second time this position happens. This is not yet a draw.} 8. Qf3 {EDIT: As the OP pointed out, technically this is the first time a threefold repetition occurs in the game.} Ng8 9. Qd1 Nf6 {Now this is a draw.} 1/2 - 1/2

However, nowadays the FIDE rules are very clear and misinterpretations on this subject should (fortunately) no longer be a problem. Article 9.2 now covers both cases, and reads:

9.2
  The game is drawn, upon a correct claim by a player having the move, when the same position for at least the third time (not necessarily by a repetition of moves):

is about to appear, if he first writes his move, which cannot be changed, on his scoresheet and declares to the arbiter his intention to make this move, or
has just appeared, and the player claiming the draw has the move.

Positions areconsidered the same if and only if the same player has the move, pieces of the same kind and colour occupy the same squares and the possible moves of all the pieces of both players are the same. Thus positions are not the same if:

at the start of the sequence a pawn could have been captured en passant.
a king or rook had castling rights, but forfeited these after moving. The castling rights are lost only after the king or rook is moved.


So, your (our) interpretation is the correct one, and there is no other possible alternative interpretation.

315: <p>A question of rulebook pedantry:</p>

<p>Effective July 2014, the FIDE has revised its <a href="http://www.fide.com/component/handbook/?id=171&amp;view=article"><em>Laws of Chess.</em></a>  As you know, the <em>Laws</em> have long allowed a player to claim a draw by repetition.  The July 2014 <em>Laws,</em> sect. 9.2, however append this curious sentence:</p>

<blockquote>
  <p>When a king or a rook is forced to move, it will lose its castling
  rights, if any, only after it is moved.</p>
</blockquote>

<p>Sect. 9.2 does not explicitly link this sentence to the draw by repetition.  The sentence floats alone.</p>

<p>Because there seems to be no other reason for the sentence to be in sect. 9.2, one tends to read it to imply that, at game's start, four <em>castling rights</em> exist&mdash;White's kingside, White's queenside, Black's kingside and Black's queenside&mdash;and that these castling rights are as much features of the position as, say, a white pawn on b3 is a feature of the position.  White's kingside castling right vanishes when Rh1 or Ke1 is first moved, or when Rh1 is captured (though, actually, sect. 9.2 does not mention the rook's capture), and cannot vanish at any other time or in any other way.  Specifically, White's kingside castling right vanishes neither (a) when White is temporarily prevented from castling kingside nor (b) when no legal continuation exists in which White could castle kingside.</p>

<p>In other words, a castling right exists even if it can never be used; and this affects when a draw can be claimed.</p>

<p>Could one read sect. 9.2 in any other way?</p>

<p>For example, this (nonsensical but technically illustrative) game is not yet a draw:</p>

<pre><code>[Title "White to open, illustrating sect. 9.2"]
[FEN "rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq - 0 1"]

1. e4 d5 2. exd5 Qxd5 3. Nc3 Qa5 4. g3 Nf6 5. Bg2 b6 6. Bxa8 Bd7 7. Qh5 Qxh5 8. Rb1 Nc6 9. b3 e6 10. Na4 Bd6 11. c3 O-O 12. Nh3 Qe5+ 13. Kf1 Qf5 14. Ke1 Qe5+ 15. Kf1 Qf5 16. Ke1 Qe5+
</code></pre>

<p>After 12... Qe5+, three castling rights have already vanished, but White's kingside right remains, <em>even though no continuation exists in which White might eventually castle.</em>  On the other hand, after 14... Qe5+ or 16... Qe5+, all four castling rights have vanished.  Therefore, triple repetition has not yet occurred.</p>

<p>Is my understanding correct?  Or is an alternate, reasonable interpretation possible?</p>

<p>Further reading:</p>

<ul>
<li><a href="http://www.chesscafe.com/archives/archives.htm#An%20Arbiter%27s%20Notebook">Geurt Gijssen.  Arbiter's Notebook.</a></li>
<li><a href="http://main.uschess.org/forums/viewtopic.php?f=2&amp;t=6113">Bill Smythe.  USCF discussion.</a></li>
</ul>
 3890: <p>My interpretation of the rules (which in this aspect I believe to be correct) is the same as yours. Although the example you provide with castling rights is conceptually a little more challenging, the problem is exactly the same as the one arising when the "en passant" rule is allowed on the first move:</p>

<pre><code>[Title "White to open, illustrating sect. 9.2"]
[FEN "rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq - 0 1"]
[Result "1/2 - 1/2"]

1. e4 e5 2. d4 Nf6 3. d5 c5 {First time this position happens.} 4. Qf3 Ng8 5. Qd1 Nf6 {Second time this "position" happens, but now white cannot take the pawn en passant, thus making actually this the first time this position happens.} 6. Qf3 Ng8 7. Qd1 Nf6 {Second time this position happens. This is not yet a draw.} 8. Qf3 {EDIT: As the OP pointed out, technically this is the first time a threefold repetition occurs in the game.} Ng8 9. Qd1 Nf6 {Now this is a draw.} 1/2 - 1/2
</code></pre>

<p>However, nowadays the FIDE <a href="http://www.fide.com/component/handbook/?id=171&amp;view=article" rel="nofollow">rules</a> are very clear and misinterpretations on this subject should (fortunately) no longer be a problem. Article 9.2 now covers both cases, and reads:</p>

<blockquote>
  <p>9.2
  The game is drawn, upon a correct claim by a player having the move, when the same position for at least the third time (not necessarily by a repetition of moves):</p>
  
  <ul>
  <li>is about to appear, if he first writes his move, which cannot be changed, on his scoresheet and declares to the arbiter his intention to make this move, or</li>
  <li>has just appeared, and the player claiming the draw has the move.</li>
  </ul>
  
  <p>Positions areconsidered the same if and only if the same player has the move, pieces of the same kind and colour occupy the same squares and the possible moves of all the pieces of both players are the same. Thus positions are not the same if:</p>
  
  <ul>
  <li>at the start of the sequence a pawn could have been captured en passant.</li>
  <li>a king or rook had castling rights, but forfeited these after moving. The castling rights are lost only after the king or rook is moved.</li>
  </ul>
</blockquote>

<p>So, your (our) interpretation is the correct one, and there is no other possible alternative interpretation.</p>
