Corel Metafile Exchange

import magic
# Libmagic can usually detect the RIFF container and CMX signature
print(magic.from_file('clipart.cmx', mime=True)) # Outputs 'image/x-cmx' or 'image/cmx'

# Manual RIFF header check:
with open('clipart.cmx', 'rb') as f:
    header = f.read(12)
    if len(header) >= 12 and header[0:4] == b'RIFF' and header[8:11] == b'CMX':
        print('Is Corel CMX: True')

const fs = require('fs');
// Manually detecting the RIFF/CMX magic bytes
const buffer = Buffer.alloc(12);
const fd = fs.openSync('clipart.cmx', 'r');
fs.readSync(fd, buffer, 0, 12, 0);
fs.closeSync(fd);
const isRIFF = buffer.toString('ascii', 0, 4) === 'RIFF';
const isCMX = buffer.toString('ascii', 8, 11) === 'CMX';
console.log('Is Corel CMX:', isRIFF && isCMX);

import (
    "bytes"
    "net/http"
)
// Native Go HTTP detection will likely only see the generic RIFF header (often mapping to 'video/avi' or 'application/octet-stream').
// You must explicitly check the bytes at offset 8.
// isCMX := len(buf) > 12 && bytes.Equal(buf[0:4], []byte("RIFF")) && bytes.Equal(buf[8:11], []byte("CMX"))

$mime = mime_content_type('clipart.cmx');
echo $mime; // Standard PHP setups will often resolve this to generic 'application/octet-stream' without custom magic database rules.