Without specific information, the most accurate advice is:
The string follows a structure common in firmware packages or hardware part numbers. dx80ce820syn213brelpkg
ce820: This likely designates the Hardware Version, Radio Chipset, or Processor Type.
syn: This usually stands for "Sync", "Synthesizer", or "System".
213b: This is likely the Version or Date Code.
relpkg: This is almost certainly an abbreviation for "Release Package".This package targets the DesignWare ARC EM11D (or similar) processor core. Without specific information, the most accurate advice is: