OP_MIX_USE "accept the chain constructed"
OP_MIX_APPEND "append a remailer to the chain"
OP_MIX_INSERT "insert a remailer into the chain"
OP_MIX_DELETE "delete a remailer from the chain"
OP_MIX_CHAIN_PREV "select the previous element of the chain"
OP_MIX_CHAIN_NEXT "select the next element of the chain"
OP_COMPOSE_MIX "send the message through a mixmaster remailer chain"