This page is intended as a terse but comprehensive summary of the Xerox Regular Expression language. Symbols Except for epsilon and other , a single symbol represents a string that consists of 16-bit Unicode characters. The string is terminated by a pair of null characters. An ordinary letter without double quotes around it is interpreted as a single character C string of the Latin-1 script. It is expanded to a string of 16-bit characters by adding an initial zero byte to each character, including the terminating null character.
Double quotes have no special meaning for symbols composed of ordinary letters.
Single symbol b. As shown in the examples above, inside double quotes any character can be written as an octal or hexadecimal number, or as a two-byte Unicode character encoded as two hexadecimal numbers. Any symbol . In writing and displaying symbol pairs, we separate the upper symbol from the lower symbol with a colon. Identity pairs can also be represented by a single symbol.