An A02 file serves as part three of a multi-volume archive, not a standalone file type, and opening it directly won’t work because the archive’s header is stored in the first segment, leading to errors like "cannot open"; the right method is to gather every piece, then open the starter file—either the main .ARJ or the .A00—so 7-Zip or WinRAR can pull data from A01, A02, etc., with issues like "next volume missing," truncated files, or CRC errors pointing to absent, incomplete, or corrupted parts; sorting the folder and verifying all numbered pieces match the same base name ensures clean extraction.

To verify what your A02 belongs to, open the folder and sort it by name, then look for identical prefixes—e.g., `backup.a00`, `backup. If you liked this posting and you would like to receive more details with regards to A02 file unknown format kindly check out the site. a01`, `backup.a02`—and check if a `.arj` file appears, which serves as the correct entry point; if there’s no `.arj` and the set starts at `.a00`, that’s the file to open via 7-Zip or WinRAR, and gaps in numbering or mismatched filenames signal missing or damaged segments that need re-copying or re-downloading before extraction succeeds.

Saying an A02 is "part 3" means it’s the third numbered segment in a multi-volume archive produced when large compressed files are split—most often into `.A00`, `.A01`, `.A02`—so A02 doesn’t hold standalone meaning but continues the same compressed stream, with the archive header stored in the first volume or a main `.ARJ`, making A02 unreadable on its own; when identical prefixes like `something.a00`, `something.a01`, and `something.a02` appear, the right method is to open the first piece so your extractor can automatically use the later parts.

An A02 file typically won’t open by itself because it’s a mid-series chunk in a split archive, and the critical metadata—archive header, index, compression specs, and integrity data—lives in the initial file like `.A00` or `.ARJ`, so when you open A02 directly, the tool finds no header at the start and throws errors like "unknown archive", even though the set may be fine; placing all volumes in one folder and opening the first one is what allows the extractor to pull A02 and the rest in sequence.

When an extractor "uses" an A02 file, it’s not interpreting A02 as a full archive because all structure lives in the starter (`.ARJ` or `.A00`), and as the tool decompresses, it requests the next sequential piece—`.A01`, then `.A02`—to continue the data stream; if A02 is mislabeled, misplaced, or broken, the process halts with messages like "data error".