ASCII Code Tables
The standard ASCII codes, 0 through 127, are common to Windows and Macintosh. These standard ASCII codes are listed in ASCII Codes 0..63 and ASCII Codes 64..127.
The ASCII codes 128 through 255 are different on Windows and Macintosh. In order to maintain platform independence, the Windows version of 4th Dimension automatically converts ASCII codes from Windows to Macintosh ASCII maps when characters are entering the 4D environment (Data entry, Edit/Paste, Import, etc.) and from Macintosh to Windows ASCII maps when characters are leaving the 4D environment (Edit/Cut or Copy, Export, etc.).
The ASCII codes 128 through 255 are listed in ASCII Codes 128..191 and ASCII Codes 192..255.
Understanding ASCII Codes and 4th Dimension
On both Macintosh and Windows, the internal database engine and the 4D language work with the Macintosh extended ASCII set. When you enter data using the keyboard (adding records, editing procedures, etc.), 4th Dimension uses the internal Altura ASCII conversion scheme to convert what comes from the keyboard (expressed using the Windows set) to the Macintosh set. For example, to enter an "é", you type ALT+0233, and 4th Dimension stores ASCII code 142 in the record. This is transparent to the end user, because when you create a search, you actually type (in the Search editor) the value for which you are looking. Therefore, the value that you typed (ALT+0233) is also translated into ASCII code 142, and you find the value.
The codes work the same when you type ALT+0233 in the Procedure editor. However, to look for a character using its ASCII code, you use the Macintosh ASCII code of the character.
QUERY (...; [MyFile]MyField="é") ` é is Alt+0233
is the same as:
QUERY (...;[MyFile]MyField=Char(142)) ` é is ASCII 142
Ascii, ISO to Mac, Mac to ISO, Mac to Win, ON EVENT CALL, Win to Mac.