Which could be used to map a value stored in a user token to a target column?

Which could be used to map a value stored in a user token to a target column?

A.
@GETENV

B.
GGHEADER

C.
GGENVIRONMENT

D.
©TOKEN

Explanation:
Reference:
http://download.oracle.com/docs/cd/E15881_01/doc.104/gg_wux_ref_v104.pdf