853-855 Subfield $z - Numbering scheme:
Subfield $z contains a six character code string used to designate the numbering scheme used on a publication. The codes allow for recording different numbering schemes at different levels of enumeration. Subfield $z follows the enumeration subfield ($a-$h) to which it applies.
Type of designation: The first one-character code indicates whether the numbering is a number, letter or combined (number first or letter first). Combined should only be used when one of the elements is a constant designation (e.g., 1a, 2a, 3a), rather than actually two different levels of enumeration (e.g., 1a, 1b, 1c).
a - Number
b - Letter
c - Combined, number first
d - Combined, letter first
e - Symbol or special character
Case: The second one-character code indicates if a numbering scheme is conveyed as alphas and applies both to those coded in the previous position as "b" or to Roman numerals.
a - No case
b - Lower case
c - Upper case
d - Mixed case
Script Code/Type Code: The third through sixth positions indicate either the script used in the numbering scheme or, for numerals or symbols that are not in alternate scripts, the type of numeral or symbol used. The script code is a four-character code from the list at: www.unicode.org/iso15924/. The type code is as follows (# means "blank"):
an## - Arabic numeral
rn## - Roman numeral
sy<symbol># - Symbol
Examples:
853 20 $81$av.$bissue$i(year)$j(month)$k(day)$ww$zaaarab
863 41 $81.1$a37$b1232$i1970$j12$k31
[The numbering scheme used is an Arabic alternate script.]
853 20 $81$av.$bno.$u26$vr$ww$x0101$yow05we$zaaan##
863 41 $81.1$a18$b7
[The numbering scheme used is Arabic numeral.]
853 20 $81$aannee$b(*)$u12$vr$cpt.$u2$vr$zbcLatn$i(year)$ws$x01
863 41 $81.1$a8$b3$cB
[Asterisk used as a convention for noncaptioned level. Numbering scheme of 3rd level is uppercase alphabetic Latin script letter.]
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