Some Private Use Area code points for the additional chess pieces of
D. Pietro Carrera for use in chess diagrams for his version of the game.

This document lists some Private Use Area code points for the additional chess pieces of D. Pietro Carrera for use in chess diagrams for his version of the game.

This list is a specialised optional use supplement to the following document.

Some Private Use Area code points for chess pieces for use in chess diagrams.

This list, the code points being entirely the choice of the present author, is published by the present author. The code points chosen are only as consistent amongst end users as end users choose to make them. These code points are not a "standard". They are simply provided on the basis that a list is better than no list, in that the existence of a list will hopefully help in producing Unicode compatible representations of chess diagrams with those Unicode compatible representations compatible with each other.

This document provides code points for the additional pieces of D. Pietro Carrera which date from the 17th Century.

The information concerning the pieces is available in the Carrera's Chess web page.

This list of code points is for symbols for producing chess diagrams, with all symbols being specified as being upon a square body, as with a metal type chess fount.

Code points U+E5A0 through to U+E5AF are used for these symbols.

The Private Use Area code points are suitable for use with ordinary TrueType founts.

In order that readers who are using OpenType technology may use ZWJ sequences in order to design chess founts I am also including ZWJ sequences for each piece.

These ZWJ sequences each include a regular Unicode code and a Private Use Area chess zero width operator. Eight such chess zero width operators are defined in the document Some Private Use Area code points for chess pieces for use in chess diagrams. of which this present document is a specialised optional use supplement.

These ZWJ sequences involve the use of some regular Unicode codes, yet each such sequence also involves a Private Use Area code within the sequence. This would mean that using the sequence with a fount which recognizes all regular Unicode characters yet which does not recognize the ZWJ sequences in this document may well give a reasonable indication that a chess diagram is intended and, indeed, allow an observant person to deduce the total meaning of the diagram. Naturally, if that fount has some different set of characters in use for the Private Use Area code points or has a black rectangle appear as an unknown character, then the display will be less elegant than if the fount displays all Private Use Area characters as zero width.

An issue is that these ZWJ sequences do not default to individual characters in the way that, say, a sequence of c ZWJ t would default to displaying c t. However, I feel that it is reasonable for me to publish Private Use definitions of ZWJ sequences which involve a regular Unicode character where the default of just the characters is not a correct display provided that at least one of the characters in the ZWJ sequence is itself a Private Use Area character. This means that the Private Use nature of the usage of such a ZWJ sequence in a plain text file would be apparent.

The code point for the ZWJ item is U+200D. The full name is ZERO WIDTH JOINER.

Here are the code point and chess diagram symbol pairings for the additional chess pieces of D. Pietro Carrera for use in chess diagrams for his version of the game.

Please note that I have provided the ZWJ sequences in the hope that they will be useful to people using OpenType technology. I have not used OpenType technology myself as of the date of this document. My specification of the ZWJ sequences is based upon reading documentation on the http://www.unicode.org website. However, I have included the ZWJ sequences in the hope that they will be useful to any readers knowledgable of OpenType technology who would like to try them out. In the event of any problems with the sequences stated, I would be pleased to receive notification by email.

The presumption is that all of these chess diagram symbols are square. I have included code points for the pieces as free standing, so that code points for free standing pieces exist, in case any particular fount designer chooses to implement "upon a white square" other than as surrounded entirely by space.

The ZWJ sequences also make use of the following regular Unicode code points from the Geometric shapes section.

U+25C6 BLACK DIAMOND
U+25C7 WHITE DIAMOND
U+25CB WHITE CIRCLE
U+25CF BLACK CIRCLE

These are used so that a display of a chess diagram using the ZWJ sequences below with a Unicode fount but without the sequences below defined within the fount will hopefully produce a display of which the meaning may be deduced by a knowledgable person.

For the avoidance of doubt, there is no intention to suggest that a diamond or a circle should be used to represent a champion or a centaur. These symbols are used simply because I wanted to use some regular Unicode symbols which would be likely in practice to appear in a fount upon a square body and where there exist in regular Unicode both white and black versions of the same shape. Diamonds and circles seemed suitable choices from amongst the choices available. In the event of a diagram set using the ZWJ sequences being displayed with a full regular Unicode fount with no additions for these chess pieces, then at least a decipherable diagram should be shown, even if the display is not as ideally intended.

U+E5A0	WHITE CHESS CARRERA CHAMPION	U+25C7 ZWJ U+E5BE
U+E5A1	BLACK CHESS CARRERA CHAMPION	U+25C6 ZWJ U+E5BE
U+E5A2	WHITE CHESS CARRERA CHAMPION UPON A WHITE SQUARE	U+25C7 ZWJ U+E5B8
U+E5A3	BLACK CHESS CARRERA CHAMPION UPON A WHITE SQUARE	U+25C6 ZWJ U+E5B8
U+E5A4	WHITE CHESS CARRERA CHAMPION UPON A BLACK SQUARE	U+25C7 ZWJ U+E5BB
U+E5A5	BLACK CHESS CARRERA CHAMPION UPON A BLACK SQUARE	U+25C6 ZWJ U+E5BB
U+E5A6
U+E5A7
U+E5A8	WHITE CHESS CARRERA CENTAUR	U+25CB ZWJ U+E5BE
U+E5A9	BLACK CHESS CARRERA CENTAUR	U+25CF ZWJ U+E5BE
U+E5AA	WHITE CHESS CARRERA CENTAUR UPON A WHITE SQUARE	U+25CB ZWJ U+E5B8
U+E5AB	BLACK CHESS CARRERA CENTAUR UPON A WHITE SQUARE	U+25CF ZWJ U+E5B8
U+E5AC	WHITE CHESS CARRERA CENTAUR UPON A BLACK SQUARE	U+25CB ZWJ U+E5BB
U+E5AD	BLACK CHESS CARRERA CENTAUR UPON A BLACK SQUARE	U+25CF ZWJ U+E5BB
U+E5AE
U+E5AF

Hopefully the code points in this document will be useful in producing founts for chess diagrams, with the founts being compatible with Unicode.

William Overington

20 June 2002