nals is a useful feature in G3 equipment with printing. The latent image on the drum is developed by the attraction several popular methods implemented. of charged normally black toner powder. This image is transferred to a cut sheet and fixed by the combination of heat and pressure at the output rollers. CCITT CSI/CIG/TSI signals The additional hardware required for a facsimile machine is bulky, expensive and significantly increases the size and cost. The paper, These are optional T.30 signals completely defined to allow inter- normal copier type paper, is much cheaper than thermal paper but operation between different manufacturers' machines. They are when allowing for toner, drum replacement and other consumables intended by CCITT to contain a '+' sign followed by up to 20 this saving is much reduced. numeric digits giving the subscriber's international telephone num- ber. In most implementations the user can insert/update the number Ink jet freely. The way the machine receiving the number uses it varies with manufacturer; it may be reported on the machine display, listed in Ink is a simple way to print on plain paper. The problem has been to an activity report or printed by the receive machine on the received keep the ink fluid and flowing until printed and then for it to dry copy. 60/12 Facsimile transmission Preamble Binary coded information Non-standard Called subscriber Digital facilities frame identification frame identification frame HDLC information field Facsimile Frame Facsimile Address Control information checking control (DIS) sequence G1 and G2 Basic G3 Additional G3 capability capability capabilities Preamble Flags for 1sec Selected DIS/DCS facsimile information bits Flag 0111 1110 Bits 1-10 Machine group identification, G1 to G3 Address 1111 1111 11-14 Data signalling rate, 2.4 to 14.4kbit/s Control 1100 X000 X = 0 or for final frame = 1 15 Fine resolution DIS fax control 0000 0001 16 MR coding 17-18 Recording width, A4, B4, A3 19-20 Recording length, A4, B4, unlimited 27 ECM 31 T.6 (MMR) coding