3 X86 X64 Pt-br [better] | Full Windows 8.1 Aio Update

This signifies that the ISO file contains both architecture types:

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stands for All-In-One . Unlike standard ISO images that contain only one edition (e.g., "Core" or "Pro"), this image packs multiple variants of Windows 8.1 into a single file. FULL Windows 8.1 AIO Update 3 x86 x64 pt-BR