ILC 1 expanded class y49x

      y49x    index 

y49x	index, bibliography, catalogue
y49xb	inventory
y49xd	descriptive index
y49xdd	word index
y49xdt	title index
y49xdu	author index
y49xs	subject index
y49xs(4)  [:]	with element
y49xs(4n)	controlled terms
y49xs(4s)	subject strings
y49xs(4t)	notation
y49xs3rif	faceted subject index
y49xse	keyword index
y49xsef	folksonomy, tags
y49xsh	controlled term index from a thesaurus
y49xsj	subject headings
y49xsl	systematic index, taxonomy, classification
y49xso	ontology, semantic network

or

Facets key
0  under aspect      
1  at time           
2  in place          
3  through process   
4  made of element   
5  with organ        
6  from origin       
7  to destination    
8  like pattern      
9  of kind