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Subject: Re: PGN and variations question

Author: Dave Gomboc

Date: 23:27:12 03/01/02

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On February 25, 2002 at 01:51:16, Manfred Schubert wrote:

>On February 25, 2002 at 01:27:35, Manfred Rosenboom wrote:
>
>>Like Eelco mentioned: the move itself can't be part of the variation, because
>>the variation is an alternative line of play. E.g.: if the main line in the
>>initial position is 1.e4 and you want to mention, that 1.d4 is an alternative
>>line of play, you have to write 1. e4 (1.d4)
>
>So something like 1. e4 (1. e4) would be definitely invalid PGN? The standard is
>maximum vague about this.
>
>Crafty seems to create this, so I'll have to support the import, but I think I
>shouldn't allow creating such variations when it is consensus that it is
>illegal.
>
>
>Manfred

Why would you consider it invalid?  From the PGN spec:

8.2.5 Movetext RAV (Recursive Annotation Variation)
An RAV (Recursive Annotation Variation) is a sequence of movetext containing one
or more moves enclosed in parentheses. An RAV is used to represent an
alternative variation. The alternate move sequence given by an RAV is one that
may be legally played by first unplaying the move that appears immediately prior
to the RAV. Because the RAV is a recursive construct, it may be nested.
*** The specification for import/export representation of RAV elements needs
further development.

There is nothing prohibiting the variation to begin with the same move as the
game.  Whether it is logical or not depends upon what you're doing, of course,
but there are scenarios where you want to do exactly this.

Dave



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