So, I fetches a DMG image and was to burn it for someone… TROUBLE!!! MacigISO, UltraISO and NERo were all said to be able to write it. Failed – not a recognised format … ???
Then I planned packing it so that I could bring the image on a suitable medium to the recipient. It packed a few (siingle number) percent.
Found TransMac (http://www.acutesystems.com/scrtm.htm) which made me realise this was a compressed DMG file.
So now you know; DMG images can be compressed. Expand them (“depack” for all I care) and then burn the image with your favourite piece of software ….