Publication: Magyar Közlöny
Issue: MK-2009-104 (Year: 2009, Number: 104)
Era: 2004-2010
Section: 
Paragraph Index: 2050

b) a combined station which has no P bit outstanding, and which has transmitted one or more frames for which responses are anticipated shall start a time-out function to detect the no-response condition. The time-out function shall cease when an I- or S-frame is received with the N(R) higher than the last received N(R) (actually acknowledging one or more I-frames). 8.6.5 Common ICAO data interchange network (CIDIN) 8.6.5.1 INTRODUCTION Note 1.— The common ICAO data interchange network (CIDIN) is an element of the aeronautical fixed service (AFS) which uses bit-oriented procedures, store and forward techniques and packet switching techniques based on CCITT Recommendation X.25 to carry messages of specific applications of the AFS such as AFTN and operational meteorological information (OPMET). Part I Annex 10 — Aeronautical Communications I-8-23 22/11/07 Note 2.— The CIDIN provides a reliable common network service for the conveyance of application messages in binary or text form to air traffic service providers and aircraft operating agencies. 8.6.5.1.1 CIDIN entry and exit centres or stations shall be used to connect application entities to the CIDIN. Note.— The interfacing between CIDIN and application entities is a matter for local implementation. 8.6.5.1.2 CIDIN relay centres shall be used to forward packets between CIDIN entry and exit centres or stations which are not directly connected. 8.6.5.2 GENERAL 8.6.5.2.1 There shall be four protocol levels defined to control the transfer of messages between CIDIN switching centres: — the data link protocol level — the X.25 packet protocol level — the CIDIN packet protocol level — the CIDIN transport protocol level. Note 1.— The relationship of the terms used is shown in Figures 8-1 and 8-2. Note 2.— The details of CIDIN communication procedures and system specifications, as implemented in Europe, are shown in the EUR CIDIN Manual (EUR Doc 005). 8.6.5.2.2 THE DATA LINK PROTOCOL LEVEL 8.6.5.2.2.1 X.25 packets to be transferred between two CIDIN switching centres or a CIDIN switching centre and a packet switched data network, shall be formatted into data link frames. 8.6.5.2.2.2 Each data link frame shall consist of a data link control field (DLCF), possibly followed by a link data field, and shall be terminated by a frame check sequence and flag (being the second part of the DLCF). If a link data field is present, the frame shall be denoted as an information frame. 8.6.5.2.2.3 X.25 packets shall be transmitted within the link data field of information frames. Only one packet shall be contained in the link data field. 8.6.5.2.3 THE X.25 PACKET PROTOCOL LEVEL 8.6.5.2.3.1 Each CIDIN packet to be transferred on CIDIN circuits between CIDIN switching centres shall be formatted into one X.25 packet. When a packet switched data network is used, it shall be permissible to format the CIDIN packet into more than one X.25 packet. 8.6.5.2.3.2 The integrity of each CIDIN packet shall be preserved by the X.25 packet protocol by mapping each CIDIN packet onto one complete X.25 packet sequence, as defined in CCITT Recommendation X.25. 8.6.5.2.3.3 Each X.25 packet shall consist of an X.25 packet header, possibly followed by a user data field (UDF). Annex 10 — Aeronautical Communications Volume III 22/11/07 I-8-24 8.6.5.2.3.4 The X.25 packet protocol is based on the application of virtual circuit procedures. A virtual circuit shall be defined as a logical path between two CIDIN switching centres. If a packet switched data network is used to interconnect two CIDIN switching centres, the procedure shall provide full compatibility with the procedures to be followed for virtual circuits according to CCITT Recommendation X.25. 8.6.5.2.4 THE CIDIN PACKET PROTOCOL LEVEL 8.6.5.2.4.1 Each transport header and the associated segment shall be preceded by a CIDIN packet header. No further segmentation of the CIDIN message shall be used between transport protocol level and CIDIN packet protocol level. Both headers, therefore, shall be used in combination. Together they shall be referred to as the communications control field (CCF). Together with the message segment they form CIDIN packets that shall be transmitted from entry centre to exit centre(s), when necessary through one or more relay centres, as an entity. 8.6.5.2.4.2 CIDIN packets of one CIDIN message shall be relayed independently via predetermined routes through the network thus allowing alternative routing on a CIDIN packet basis as necessary. 8.6.5.2.4.3 The CIDIN packet header shall contain information to enable relay centres to handle CIDIN packets in the order of priority, to transmit the CIDIN packets on the proper outgoing circuit(s) and to duplicate or multiplicate CIDIN packets when required for multiple dissemination purposes. The information shall be sufficient to apply address stripping on the exit addresses as well as on the addressee indicators of messages in AFTN format. 8.6.5.2.5 THE TRANSPORT PROTOCOL LEVEL 8.6.5.2.5.1 Information exchanged over the CIDIN shall be transmitted as CIDIN messages. 8.6.5.2.5.2 The length of a CIDIN message shall be defined by the CIDIN packet sequence number (CPSN). The maximum permissible length is 215 packets which in effect results in no practical limitation. 8.6.5.2.5.3 If the length of a CIDIN message and its transport and packet headers (as defined below) exceeds 256 octets, the message shall be divided into segments and placed in the CIDIN user data field of CIDIN packets. Each segment shall be preceded by a transport header containing information to enable the re-assembly of the CIDIN message at the exit centre(s) from individually received segments and to determine further handling of the received complete CIDIN message. 8.6.5.2.5.4 All segments of one CIDIN message shall be provided with the same message identification information in the transport header. Only the CPSN and final CIDIN packet (FCP) indicator shall be different. 8.6.5.2.5.5 Recovery of messages shall be performed at the transport level. Part I Annex 10 — Aeronautical Communications I-8-25 22/11/07 TABLES FOR CHAPTER 8 Table 8-1. International Telegraph Alphabets No. 2 and No. 3 Impulses 5-unit code Number of signal Letter case Figure case Start Stop International Code No. 2 A — A ZZAAA Z B ? A ZAAZZ Z C : A AZZZA Z D Note 1 A ZAAZA Z E A ZAAAA Z F A ZAZZA Z G A AZAZZ Z H A AAZAZ Z I A AZZAA Z J Attention signal A ZZAZA Z K ( A ZZZZA Z L ) A AZAAZ Z M . A AAZZZ Z N , A AAZZA Z O A AAAZZ Z P A AZZAZ Z Q A ZZZAZ Z R A AZAZA Z S ’ A ZAZAA Z T A AAAAZ Z U A ZZZAA Z V = A AZZZZ Z W A ZZAAZ Z X / A ZAZZZ Z Y A ZAZAZ Z Z + A ZAAAZ Z carriage return A AAAZA Z line feed A AZAAA Z letters A ZZZZZ Z figures A ZZAZZ Z space A AAZAA Z unperforated tape A AAAAA Z signal repetition signal α signal ß Sign Closed circuit Double current A No current Negative current Z Positive current Positive current Note 1.— Used for answer-back facility. Annex 10 — Aeronautical Communications Volume III 22/11/07 I-8-26 Table 8-2. International Alphabet No. 5 (IA-5) (international reference version) b7 b6 b5 b4 b3 b2 b1 NUL TC7 (DLE) SP @ P ` p TC1 (SOH) DC1 ! A Q a q TC2 (STX) DC2 " f B R b r TC3 (ETX) DC3 # C S c s TC4 (EOT) DC4 ¤ d D T d t TC5 (ENQ) TC8 (NAK) % E U e u TC6 (ACK) TC9 (SYN) & F V f v BEL TC10 (ETB) ' f G W g w FE0 (BS) CAN ( H X h x FE1 (HT) EM ) I Y i y FE2c (LF) SUB * : J Z j z FE3 (VT) ESC + ; K [ k { FE4 (FF) IS4 (FS) f , < L \ l | FE5c (CR) IS3 (GS) – = M ] m } SO IS2 (RS) . > N ^ f n ¯ e SI IS1 (US) / ? O __ o DEL NOTES Note 1.—The format effectors are intended for equipment in which horizontal and vertical movements are effected separately. If equipment requires the action of CARRIAGE RETURN to be combined with a vertical movement, the format effector for that vertical movement may be used to effect the combined movement. Use of FE 2 for a combined CR and LF operation is not allowed for international transmission on AFS networks. Note 2.—The symbol ¤ does not designate the currency of a specific country. Note 3.—Position 7/14 is used for graphic character ¯ (OVERLINE), the graphical representation of which may vary according to national use to represent (TILDE) or another diacritical sign provided that there is no risk of confusion with another graphic character included in the table. Note 4.—The graphic characters in position 2/2, 2/7, 2/12 and 5/14 have respectively the significance of QUOTATION MARK, APOSTROPHE, COMMA and UPWARD ARROW HEAD; however, these characters take on the significance of the diacritical signs DIAERESIS, ACUTE ACCENT, CEDILLA and CIRCUMFLEX ACCENT when they are preceded or followed by the BACKSPACE character (0/8). Note 5.—When graphical representation of the control characters of IA-5 is required, it is permissible to use the symbols specified in International Organization for Standardization (ISO) Standard 2047-1975. Part I Annex 10 — Aeronautical Communications I-8-27 22/11/07 CONTROL CHARACTERS GRAPHIC CHARACTERS Abbreviation Meaning Position in the code table Graphic Note Name Position in the code table ACK Acknowledge 0/6 (space) Space (see 7.2) 2/0 BEL Bell 0/7 ! Exclamation mark 2/1 BS Backspace 0/8 " Quotation mark, Diaeresis 2/2 CAN Cancel 1/8 # Number sign 2/3 CR Carriage return* 0/13 ¤ Currency sign 2/4 DC Device control – % Percent sign 2/5 DEL Delete 7/15 & Ampersand 2/6 DLE Data link escape 1/0 ' Apostrophe, Acute accent 2/7 EM End of medium 1/9 ( Left parenthesis 2/8 ENQ Enquiry 0/5 ) Right parenthesis 2/9 EOT End of transmission 0/4 * Asterisk 2/10 ESC Escape 1/11 + Plus sign 2/11 ETB End of transmission block 1/7 , Comma, Cedilla 2/12 ETX End of text 0/3 – Hyphen, Minus sign 2/13 FE Format effector – . Full stop (period) 2/14 FF Form feed 0/12 / Solidus 2/15 FS File separator 1/12 : Colon 3/10 GS Group separator 1/13 ; Semi-colon 3/11 HT Horizontal tabulation 0/9 < Less-than sign 3/12 IS Information separator – = Equal sign 3/13 LF Line feed* 0/10 > Greater-than sign 3/14 NAK Negative acknowledge 1/5 ? Question mark 3/15 NUL Null 0/0 @ Commercial 'at' 4/0 RS Record separator 1/14 [ Left square bracket 5/11 SI Shift-in 0/15 \ Reverse solidus 5/12 SO Shift-out 0/14 ] Right square bracket 5/13 SOH Start of heading 0/1 ^ Upward arrow head, SP Space 2/0 Circumflex accent 5/14 STX Start of text 0/2 __ Underline 5/15 SUB Substitute character 1/10 ` Grave accent 6/0 SYN Synchronous idle 1/6 { Left curly bracket 7/11 TC Transmission control – | Vertical line 7/12 US Unit separator 1/15 } Right curly bracket 7/13 VT Vertical tabulation 0/11 ¯ Overline, Tilde 7/14 * See Note 1. DIACRITICAL SIGNS In the character set, some printing symbols may be designed to permit their use for the composition of accented letters when necessary for general interchange of information. A sequence of three characters, comprising a letter, BACKSPACE and one of these symbols, is needed for this composition, and the symbol is then regarded as a diacritical sign. It should be noted that these symbols take on their diacritical significance only when they are preceded or followed by the BACKSPACE character: for example, the symbol corresponding to the code combination 2/7 (') normally has the significance of APOSTROPHE, but becomes the diacritical sign ACUTE ACCENT when it precedes or follows the BACKSPACE character. NAMES, MEANINGS AND FONTS OF GRAPHIC CHARACTERS At least one name is assigned to denote each of the graphic characters. These names are intended to reflect their customary meanings and are not intended to define or restrict the meanings of graphic characters. No particular style or font design is specified for the graphic characters. UNIQUENESS OF CHARACTER ALLOCATION A character allocated to a position in the table may not be placed elsewhere in the table. Annex 10 — Aeronautical Communications Volume III 22/11/07 I-8-28 FUNCTIONAL CHARACTERISTICS RELATED TO CONTROL CHARACTERS Some definitions given below are stated in general terms and more explicit definitions of use may be needed for specific implementation of the code table on recording media or on transmission channels. These more explicit definitions and the use of these characters are the subject of ISO publications. General designations of control characters The general designation of control characters involves a specific class name followed by a subscript number. They are defined as follows: TC — Transmission control characters — Control characters intended to control or facilitate transmission of information over telecommunication networks. The use of the TC characters on the general telecommunication networks is the subject of ISO publications. The transmission control characters are: ACK, DLE, ENQ, EOT, ETB, ETX, NAK, SOH, STX and SYN. FE — Format effectors — Control characters mainly intended for the control of the layout and positioning of information on printing and/or display devices. In the definitions of specific format effectors, any reference to printing devices should be interpreted as including display devices. The definitions of format effectors use the following concept:

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