The term is a technical specification. An ISO file is an exact sector-by-sector copy of an optical disc (CD/DVD). The Netter v30iso is typically a ~600MB to 1.2GB file. Here is why this matters for long-term access:
Detailed representations of reproductive and urinary systems. Limbs: Extensive musculature and innervation studies. Why Netter Remains Essential netter interactive atlas of human anatomy v30iso
The term "ISO" refers to an identical digital copy (an image file) of the original CD-ROM or DVD-ROM disc. The term is a technical specification