Which of the following are true about Chain Indexing

(A). False link does not represent a subject but is an indicator of the type of facet to follow. 

(B). Unsought Link is a substantive heading on which either there is no published material or a user is unlikely to ask or look for material on that subject in the library.

(C). A Sought Link is a link that is neither false nor unsought.

(D). A Lower Link is a bypassed link that occurs in an un-modulated chain.