Terminal devices and a method of transferring sets of transmission document information in a network system between terminal devices such as portable devices which can be grouped together into a plurality of different groups is provided. A terminal device can store capability information relative to a specific type of data that can be received and outputted. The terminal device can receive an inquiry from another terminal device as to the capability information and can transmit the capability information when appropriate to the inquiring terminal device. Various types of capability information can be stored, depending upon the particular capabilities of the terminal device such as picture data, audio data and character data to enable the terminal device to be an e-mail terminal.