Anyone know the correct syntax for specifying a floppy image in the /tftpboot/pxelinux.cfg/default file?

I am trying to use:

label Dos Bootdisk MENU LABEL Dos bootdisk FDIMAGE discimage.img

But when I select it the menu, I get a message saying "Automatic boot in 30 seconds" and nothing happens.

I would use:

label Dos Bootdisk 2 MENU LABEL Dos bootdisk 2 kernel memdisk append initrd=discimage.img

but this is a 2.88meg floppy and memdisk wont boot it?

Thanks! jlc