The format is a macOS Disk Image. Apple sometimes packages manuals as "Books" or applications that open in the Apple Books app, which is why they may be distributed as a .dmg installer rather than a straight PDF.
: This paper analyzes how websites use cryptographic hashes (like SHA256) to verify download integrity. It is available through the ACM Digital Library . pages 562 dmg download verified
If you have previously purchased Pages (when it was a paid app before 2013) or if your Apple ID is associated with an older version, you can find it in your . The format is a macOS Disk Image