code: public function canRead($pFilename)
      {
          // Check if file exists
          try {
              $this->openFile($pFilename);
          } catch (Exception $e) {
              return false;
          }
  
          // Read sample data (first 2 KB will do)
          $data = fread($this->fileHandle, 2048);
  
          // Count delimiters in file
          $delimiterCount = substr_count($data, ';');
          $hasDelimiter = $delimiterCount > 0;
  
          // Analyze first line looking for ID; signature
          $lines = explode("\n", $data);
          $hasId = substr($lines[0], 0, 4) === 'ID;P';
  
          fclose($this->fileHandle);
  
          return $hasDelimiter && $hasId;
      }
docs: Validate that the current file is a SYLK file.
  
  @param string $pFilename
  
  @return bool