Mavericks Os X 10.9.x Dmg //top\\

That’s an interesting angle — and you're right to notice something unique.
One of the more interesting technical features of the OS X Mavericks (10.9.x) DMG (compared to previous and later versions) is related to how Apple packaged and delivered it.

Select Mavericks: The script will list available macOS versions. Look for macOS 10.9 Mavericks. It usually has a specific index number. Type the index number for Mavericks and press Enter. mavericks os x 10.9.x dmg

Locate the DMG: The script will download the installer and save it as a DMG file in the current directory. This DMG contains the "Install OS X Mavericks.app". That’s an interesting angle — and you're right

When Apple released OS X Mavericks (version 10.9) in October 2013, it marked a significant shift in the company’s software strategy. For the first time, Apple made a Mac operating system completely free. Mavericks wasn't just about new features; it was about performance, efficiency, and extending battery life for portable Macs. InstallESD

installer for Mavericks (final version 10.9.5) requires specific baseline hardware: OS X Mavericks - Technical Specifications - Apple Support

  • InstallESD.dmg — the top-level disk image Apple included in the app bundle. It is the source for building installers but in Mavericks it is not directly a fully-bootable single-image installer in the same way as earlier releases.
  • BaseSystem.dmg — small, bootable OS X base used by the installer environment (typically mounted as “OS X Base System” when you attach InstallESD.dmg).
  • Sparseimage / sparsebundle — writable containers used when assembling a custom installer image (you create and resize them to add Packages).
  • UDZO / UDRO / UDSP / UDTO — hdiutil formats (compressed read-only, read-only, read/write sparse, and CDR/ISO conversion). Use UDZO or UDSP when producing stable read-only images for distribution.
  • .chunklist and certificates — used by the firmware/installer to verify integrity and authenticity of the payload.

Alternative: Archive.org (Legacy)

If you cannot use the command line tool, reputable archives like the Internet Archive often host original installation media.

3. It contained a hidden BaseSystem.dmg that was compressed differently

Inside the InstallESD.dmg was a BaseSystem.dmg — a minimal bootable recovery system.
Mavericks used a lzfse-like compression (not yet lzfse named, but an early variant) for some of the system files inside the DMG, making the image smaller than Mountain Lion’s while maintaining boot speed.