066 Subfield $b - Primary G1 character set:

Subfield $b contains a code identifying the primary extension character set. The code is composed of the Intermediate and Final characters of the escape sequence that designates and invokes the default G1 character set. Since ANSEL is the MARC default set, if it is the primary extended set it does not need to be identified in this subfield.

Examples:

066 ##$b$)1

[The Intermediate characters in the designation sequence are hex 24 hex 29 (ASCII graphics "$)") that identify the character set as multiple bytes per character and its use as a G1 set, and the Final character is hex 31 (ASCII graphic "1") that identifies the East Asian character code for bibliographic use (ANSI/NISO Z39.64-1989 (R1995)).]

066 ##$b)Q

[The Intermediate character in the designation sequence is hex 29 (ASCII graphic ")") that identifies the character set as one byte per character and its use as a G1 set, and the Final character is hex 51(ASCII graphic "Q") that identifies the Extended Cyrillic character set.]