The CDM file is a disk image file generated by NTI CD-Maker, a program used to copy and create DCs.
NTI CD-Maker has since changed its name to NTI Media Maker and these files are still supported.
.cdm File
Extension
Developer:
NTI
File category:
What are cdm files & how to open them - NTI CD-Maker Image File
File category:
Developer:
NTI