X Bitmap (Legacy MIME Alias)

import magic
# Libmagic can identify XBM files by scanning the text content for C preprocessor macros
print(magic.from_file('icon.xbm', mime=True)) # Outputs 'image/x-xbitmap' or 'text/plain'

const fs = require('fs');
// Reading the first few bytes to check for the '#define' C preprocessor directive
const buffer = Buffer.alloc(7);
const fd = fs.openSync('icon.xbm', 'r');
fs.readSync(fd, buffer, 0, 7, 0);
fs.closeSync(fd);
const isXBM = buffer.toString('ascii') === '#define';
console.log('Is X Bitmap (XBM):', isXBM);

import (
    "bytes"
    "net/http"
)
// Native Go HTTP detection will likely return text/plain because XBM is valid source code.
// Check directly for the #define prefix:
// isXBM := bytes.HasPrefix(buf, []byte("#define"))

$mime = mime_content_type('icon.xbm');
echo $mime; // May return 'image/x-xbm', 'image/x-xbitmap', or 'text/plain' depending on the system's magic database rules.