code: public void setTag(String tag) throws IllegalArgumentException {
  		if (tag == null
  				|| (tag != null && (tag.length() < 1 || tag.length() > 32))) {
  			throw new IllegalArgumentException(
  					"The tag must not be null, the length between 1..32");
  		}
  
  		this.tag = tag;
  	}
docs: Set the tag that is used for the TAG field in the MSG part of the
  message. The TAG length must not exceed 32 chars.
  
  @param tag
  the tag to set
  @throws IllegalArgumentException
  if the tag is null or the length is incorrect.