Apple Partition Map

Apple Partition Map (APM) is a format that describes the partition layout of a disk. When in the form of a disk image file, it can be thought of as a container format for multiple filesystem image files.

Identification
The ASCII characters "PM" appear at offset 512, and (usually?) also at offset 1024. They may also appear at larger multiples of 512.

Software

 * HFSExplorer
 * 7-Zip [Ed. note: Seems unreliable. Supports GoldenOrchard1.2.iso but not GoldenOrchard1.0.iso.]
 * Supported natively by some Apple Macintosh operating systems.

Sample files

 * https://archive.org/details/cdrom-golden-orchard-10 → GoldenOrchard1.0.iso
 * https://archive.org/details/cdrom-golden-orchard-12 → GoldenOrchard1.2.iso

Links

 * Wikipedia article
 * Apple's Transition from Apple Partition Map to the GUID Partition Table