code: protected Set<String> extractModifNames(Set mfSet)
  	{
  		Set<String> set = new HashSet<String>();
  
  		for (Object o : mfSet)
  		{
  			ModificationFeature mf = (ModificationFeature) o;
  			if (mf.getModificationType() != null && !mf.getModificationType().getTerm().isEmpty())
  			{
  				set.add(mf.getModificationType().getTerm().iterator().next());
  			}
  		}
  		return set;
  	}
docs: Extracts terms of the modification features.
  @param mfSet set of modification features
  @return set of extracted terms