code: private int getResourceCode(String field) throws MPXJException
     {
        Integer result = m_resourceNumbers.get(field);
  
        if (result == null)
        {
           throw new MPXJException(MPXJException.INVALID_RESOURCE_FIELD_NAME + " " + field);
        }
  
        return (result.intValue());
     }
docs: Given a resource field name, this method returns the resource field number.
  
  @param field resource field name
  @return resource field number