hoolio suggested I RTFM...sigh.
From 'b class help'
[blockqoute]
type Specifies the type of data want to add to, modify, display, or delete from an external
class. This setting is required for external classes. Specify the type by including a list
of strings, values, or IP addresses. When running the command from the system prompt,
strings must be surrounded by escaped quotation marks. When running the command from the
bigpipe shell, strings must be surrounded by quotation marks (not escaped). A value is a
number that can be either positive or negative. IP addresses can be in any of the following
formats:
-- network mask < ip mask>
-- network prefixlen
-- network /
-- host
[/blockquote]
An example that saved for me:
host 192.168.1.1,
host 192.168.1.2 := "host2",
network 192.168.2.0 mask 255.255.255.0,
network 192.168.3.0 mask 255.255.255.0 := "network2",
network 192.168.4.0/24 := "network3",
Note that the CIDR notation doesn't seem to work with spaces as shown in the help, at least in my 10.2.1 HF1 version.