code: public final void setValidField(final int field, final boolean valid)
  	{
  		if (field < 0 || field >= FIELD_MASKS.length)
  			throw new KNXIllegalArgumentException("illegal field");
  		setBit(0, FIELD_MASKS[field], !valid);
  	}
docs: Sets a date/time field of the first translation item to valid or not valid.
  <p>
  A field which is valid, i.e., contains valid data, has to be set <code>true</code>,
  otherwise the field should be set not valid with <code>false</code>.<br>
  Possible fields allowed to be set valid or not valid are {@link #YEAR},
  {@link #DATE}, {@link #TIME}, {@link #DAY_OF_WEEK} and {@link #WORKDAY}.
  
  @param field field number
  @param valid <code>true</code> if field is supported and contains valid data,
  <code>false</code> otherwise