I believe those arrived during OS 4.x some time.
No, DefIcons could do this from the beginning.
Really? Other people seemed to be able to do this, too. I was always frustrated with the limited 6 items that were there.
So, does one simply create new default icons, for say def_CD1.info or def_Zip1.info, etc. and copy them to Envarc.sys? Can this work for def_sound.info, def_pic.info, def_IFF.info?