For some strange reason, ifup-ppp in initscripts-5.00 first insists on 
/etc/sysconfig/network-scripts/chat-$DEVICE being present, but then does
the following:

if [ -z "$WVDIALSECT" ] ; then
  CHATSCRIPT=/etc/sysconfig/network-scripts/chat-$DEVNAME
  [ -f $CHATSCRIPT ] || {
    CHATSCRIPT=/etc/sysconfig/network-scripts/chat-$PARENTDEVNAME
  }
else
...

Most parts of the initscripts package are OK with ifcfg-xxx containing
DEVICE=yyy (with xxx and yyy being completely unrelated and yyy being the
"real" device name - eth0, ppp0, etc), but not PPP.

The reason I want to do this is to be able to bring ppp0 up using "ifup
<ISP name>" and have several ifcfg files for different ISPs with
DEVICE=ppp0 in all of them.