SPSS data file file signature
Magic number at the start of the file · $FL2
An SPSS system file (.sav) starts with the four-byte marker $FL2, followed by the header records that store variable and value labels alongside the data.
What this magic number means
A magic number is a short, fixed run of bytes at a known position that tells a program what a file really is, no matter what the filename says. If a file starts with the bytes 24 46 4C 32 (the text $FL2), it is a SPSS data file file.
Formats that use the 24 46 4C 32 signature
These file types in our database carry this signature:
How to check a file's signature
You can read the first bytes of any file yourself. The magic bytes are shown in hex, the same way this page lists them.
Linux & macOS
- xxd -l 16 example.sav
- hexdump -C -n 16 example.sav
- file example.sav
Windows (PowerShell)
- Format-Hex -Path example.sav -Count 16
Python
- open("example.sav","rb").read(4).hex()
In your browser
- Drop the file into the WhatFileType identifier, which reads the signature without uploading it.
Frequently asked questions
What is the SPSS data file file signature?
SPSS data file files start with the hex bytes 24 46 4C 32 ($FL2 in ASCII). This magic number identifies the format regardless of the file's name or extension.
How do I check a file's magic number?
Open the file in a hex editor, or run a command such as xxd -l 16 example.sav on Linux or macOS, or Format-Hex -Path example.sav -Count 16 in Windows PowerShell, and read the first bytes.
Can a file fake the SPSS data file signature?
Renaming a file does not change its bytes, so the extension can lie but the signature usually cannot. A genuine SPSS data file file has these exact bytes; a file with the wrong bytes is not really SPSS data file, whatever its name says.