Aldus Placeable Metafile
Aldus Corperation created the Placeable Metafile to specify how a metafile is to be mapped and scaled on output devices. These files are not supported by the Windows API due to the placeable metafile having a 22-byte header.
Here is an example of a APM Header.
To playback a placeable metafile in Windows you need to save the file the open it in a Hex Editior and remove the header that starts at Offset 0x16.
Today APM belongs to Adobe Systems due to Aldus Corperation being merged with Adobe Systems in 1994.
How to open .apm files?
Software to open .apm files
What are .apm files