The Record’s Underlying Structure
•100:  10 : Garreau, Joel. 
•245:  14 : The nine nations of North America /|cJoel Garreau. 
•260:  0  : Boston :|bHoughton Mifflin,|c1981. 
•020:     : 0395291240 :|c$12.95 
•300:     : xvii, 427 p. :|bill. ;|c24 cm. 
•500:     : Includes index. 
•504:     : Bibliography: p. [397]-413. 
•596:     : 5
I know!  I know!  Eeek!  It’s the dreaded MARC record – well, at least some of  the variable fields.  The numbers on the extreme left are the tags for the fields of the records.  They’re unique to the MARC record and you’ll often see them displayed as the more human friendly “Personal Author”, “Title”, etc.  Between the colons are what are known as “indicators.”  They are truly unique to the MARC record.  From my forever dimming memory, I can only recall that the “4” means to ignore the first four character spaces or “The “ – the initial article.  The “|b” or “|c”  are known as “delimiters” and signify the beginnings of subfields of a field.