I have found that some wattcp applications will parse the value of
DOS environment variables, if they appear in a wattcp.cfg file.
Thus if you put:
my_ip=%myip%
in a wattcp.cfg file - where %myip% is the variable set to your current
dynamic IP address when you run a file like ip-up.bat or similar file,
created by epppd, some applications will be able to interpret
%myip% directly. For those writing different wattcp.cfg file for
different applications, this saves you the trouble of writing a
batch file that inserts the literal dynamic IP address into wattcp.cfg
