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A3 ISO page size 11.9" x 16.5" (303 mm x 420 mm)
A4 ISO page size 8.25" x 11.6" (210 mm x 297 mm)
B4 ISO page size 10" x 14" (255 mm x 353 mm)
CED CallED tone; the 3-second 2100 Hz tone a called fax terminal places on the line to indicate that the called station is a fax terminal.
CIG CallInG subscriber identification; used in fax polling by the calling fax terminal to identify itself. The CIG is defined by ITU T.30 as the calling station's international telephone number, and can contain up to 20 characters.
CNG CalliNG tone; the 0.5 second, 1100 Hz tone placed on the line every 3 seconds until CED is received. The CNG tone indicates a fax terminal is calling.
CSI Called Subscriber Identification; an optional frame used by the called fax terminal to give its international telephone number. which can contain up to 20 characters.
DCS Digital Command Signal; the set-up command used by the calling fax terminal in response to DIS. The DCS determines the attributes of the fax transmission to follow (transmission speed, resolution, etc.).
DIS Digital Identification Signal; used by the called fax terminal to communicate its capabilities to the calling fax terminal.
document The image entity to be transmitted; it is contained in a single file, and can contain more than one page. Documents to be transmitted by NaturalFax must be in TIFF-F format. Documents received by NaturalFax are stored in TIFF-F format.
document queue A NaturalFax data structure that contains references to documents. A document queue must be either a send queue or a receive queue; only send queues can be sent, and only receive queues can be used to receive documents.
DTC Digital Transmit Command; used by the calling fax terminal to poll the called fax terminal.
fax license unit Fax license units are used to measure and control the number of active fax units in a system. If an application does not explicitly allocate fax license units, the NaturalFax functions will automatically allocate fax license units as required.
fax session An active fax session is the transmitting or receiving of document queues. The portion of a fax call which begins with the called fax terminal advertising its capabilities (Phase B) and ends with the calling fax terminal commanding a disconnect (Phase E).
Group 3 Fax A fax protocol published in 1980 by the ITU. Group 3 protocol is specified in several standards: T.4 specifies the image-transfer protocol, T.30 specifies the session-management procedures which support the establishment of a fax transmission. Since Group 3 protocol is specified for the switched analog network, and it is an all-digital procedure, it must use modems.
ITU The International Telecommunications Union (ITU) is the international standards body for telecommunications.
Non Standard Facilities Frames
ITU T.30 allows a non-standard message, one whose contents are not specified by T.30, to be included with most negotiations. These non-standard frames are called NSF (Non-Standard Facilities) when the called fax terminal sends DIS, NSS (Non-Standard Set Up) when the calling fax terminal responds to DIS with DCS, and NSC (Non-Standard facilities Command) when commanding the called fax terminal to send (a poll). A non-standard frame begins with the country code of the manufacturer, the manufacturer's code, and any additional ASCII information (limited by allowable transmission time of three seconds). The non-standard frame transmitted by the remote terminal will only be read if the first three bytes match the Country Code and Manufacturer's ID parameters for this terminal.
Phase A The call set up phase of the T.30 protocol
Phase B The pre-message procedure for identifying and selecting call-specific facilities in the T.30 protocol.
Phase C The image transfer phase of the T.30 protocol.
Phase D The post-message procedures (EOM and multi-document procedures) of the T.30 protocol.
Phase E The call release phase of the T.30 protocol.
polling During a fax polling operation, the calling fax terminal requests that the called fax terminal send documents to the calling fax terminal. This is also known as turnaround polling.
PRI PRocedure Interrupt; a signal to the remote fax terminal which requests the remote fax terminal to permit operator interaction. A PRI signal is used to request that the remote fax terminal allow operator intervention, such as voice communications over the handset, and not hang up the call at the end of a fax session..
receive queue A NaturalFax document queue for receiving documents transmitted from one fax terminal to another. A receive queue must have an allocated entry for each document to be received. Only names of files that do not exist can be enqueued in a receive queue; the file name may not be NULL.
send queue A NaturalFax document queue for sending documents from one fax terminal to another. Only files that already exist can be added to a send queue. The same file can be placed in multiple send queues simultaneously.
TIFF Tagged Image File Format; a graphics file format characterized by the use of "tags" to specify the format of the file.
TIFF-F A class of TIFF file with byte-aligned end-of-line (EOL) characters, intended for use in fax applications. It supports multipage fax documents in one file.
TSI Transmitting Subscriber Identification; used by the transmitting fax terminal to identify itself. Defined as an international telephone number that can contain up to 20 characters.
T.4 The standard which defines Group 3 image transfer fax protocol.
T.30 The ITU standard which defines the negotiating procedures and session management for Groups 1, 2, and 3 fax. T.30 divides a fax session into five phases, A through E, as defined earlier in this glossary.
V.17 The 7200/9600/12000/14400 bps modem which is used for Group 3 fax.
V.21 The 300 bps modem used for Group 3 fax negotiations.
V.27ter The 2400/4800 bps modem which is used for Group 3 fax.
V.29 The 7200/9600 bps modem which is used for Group 3 fax.
V.33 The 12000/14400 bps modem which is used for Group 3 fax.
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