documentation for the macro "classes"

Complete set of classes mostly used for iterating.

It is defined in the file essentials.m4.

m4 code:

define(`classes',
`blk_file
capability
capability2
chr_file
dir
drawable
fd
fifo_file
file
filesystem
key
lnk_file
msg
msgq
netif
netlink_kobject_uevent_socket
netlink_route_socket
netlink_selinux_socket
node
packet
packet_socket
passwd
peer
process
rawip_socket
security
sem
shm
sock_file
socket
system
tcp_socket
udp_socket
unix_dgram_socket
unix_stream_socket')