866 fields
 
a)  Enter holdings data according to ANSI⁄NISO Z39.71 and MARC21 holdings standards.
NOTE: Migrated pre-Voyager holdings statements included a space before parentheses for readability;  but for new holdings statements and when editing existing statements, follow standards and omit the space.
Example of former practice:   
v.1:no.1 (1988:Jan.)-v.6:no.12 (1993:Dec.)
 
Example of current standard:   v.1:no.1(1988:Jan.)-v.6:no.12(1993:Dec.)
 
b)  Distinguish between closed or complete multi-part items or serials, and those that are ongoing or on standing order.   If the monographic multi-part item or serial is not on s.o., enter exact summary holdings statements in 866.  Update the statement when new item records are made for added volumes⁄pieces, or when existing item records are edited.
 
If the monographic MPI or serial title is on s.o., use an open holdings statement, until the item ceases publication or the s.o. is cancelled or completed.
Example of open holdings statements:  v.1-        v.1:no.1-
(Cf.  separate rules for serials holdings).
 
c)  Do not make an 866 holdings statement for single-volume (single piece) monographs.  (But see also rules for accompanying materials.)
 
d)  Do not mix Level 3 and Level 4 data in the same 866 tag (this violates the Z39.71 standard).
 
e)  In situations where summary holdings statements require more than one 866 tag, (generally when gaps in holdings require detailed Level 4 statements interspersed between Level 3 statements), the maximum number of 866 tags allowed is around 20.
 
f)  Indicator 1 (Field encoding level)
This should match the Encoding level value in the Leader, except when both levels 3 and 4 are used in different 866 tags in the same MFHD.
Blank = No information provided
3 = Holdings level 3
4 = Holdings level 4
 
g)  Indicator 2 (Type of notation)
0 = Non-standard   [rare; may be used when standard statement cannot be created from available information]
1 = ANSI⁄NISO Z39.71  [prefer]
 
h)  Subfield 8 (Link and sequence number)
When editing an 866 tag, add subfield 8 before subfield a, and enter the value of “0” [zero].