    class
    	PROXY_INFORMATION

    General
    	cluster: transfer
    	description: "Information about proxies"
    	create: make

    Ancestors
    	HOST_VALIDITY_CHECKER

    Queries
    	host: STRING_8
    	port: INTEGER_32
    	proxy_host_ok (h: STRING_8): BOOLEAN

    Commands
    	set_host (h: STRING_8)
    	set_port (p: INTEGER_32)

    Constraints
    	host not empty
    	host valid
    	port non negative