Subfield $w in Name/Series authority records

For each position, the top line lists the title and description from the MARC21 format manual, followed by a list of codes defined. The last two lines give the notes from LC's Blue pages.

/0 - Special relationship (describes a relationship of an entity in a 4XX or 5XX field to that in the 1XX field that is more specific than the relationship implicit in the tag.)

a - Earlier heading
b - Later heading
d - Acronym 
f - Musical composition 
g - Broader term 
h - Narrower term 
i - Reference instruction phrase in subfield $i 
n - Not applicable 
r - Relationship designation in $i or $4 
t - Immediate parent body

4XX Notes: DNU¹⁾ a,b,d,f,g,h,i,t. Code d may occur in NAF records created before 1981.
5XX Notes: DNU d,f,h,i,t. Codes d and f (5XX) may occur in NAF records created before 1981.

/1 - Tracing use restriction (specifies the authority reference structure in which the use of a 4XX or 5XX field to generate a cross reference is appropriate.)

a - Name reference structure only 
b - Subject reference structure only 
c - Series reference structure only 
d - Name and subject reference structures 
e - Name and series reference structures 
f - Subject and series reference structures 
g - Name, subject, and series reference structures 
h - No reference structures 
n - Not applicable 

4XX Notes: DNU a,b,c,d,e,f,g.
5XX Notes: DNU a,b,c,d,e,f,g.

/2 - Earlier form of heading (indicates whether the heading in the 4XX field is an earlier form in which the name or subject was established either in the relevant national authority file or in an authority file other than the national authority file.)

a - Pre-AACR 2 form of heading (national name authority file) 
e - Earlier established form of heading (national authority file) 
o - Earlier established form of heading (other authority file) 
n - Not applicable 

4XX Notes: DNU o. Obsolete codes b, c, and d map appear in records created before 1981.
5XX Notes: DNU a,e,o.

/3 - Reference display (enables the generation or suppression of a cross reference from a 4XX or 5XX field.)

a - Reference not displayed 
b - Reference not displayed, field 664 used 
c - Reference not displayed, field 663 used 
d - Reference not displayed, field 665 used 
n - Not applicable 

4XX Notes: DNU c,d. Code d may occur in NAF records created before 1981.
5XX Notes: DNU b,d. Code d may occur in NAF records created before 1981.