Skip to content

Appendix 7: Document Release History

Date Doc Version Status / Major Changes
10 Oct 1999 1.0 (Draft) Protocol Version 1.0. First public draft release.
3 Dec 1999 1.0.1g Protocol Version 1.0. Second public draft release. Much extended, incorporating packet format layouts, APRS symbol tables, compressed data format, Mic-E format, telemetry format.
30 Apr 2000 1.0.1m Protocol Version 1.0. Third public draft release. Major additions/changes to the draft 1.0.1g specification: * Added a section on Map Views and Range Scale. * Changed Destination Address SSID description (specifying generic APRS digipeater paths) to apply to all packets, not just Mic-E packets. * Changed APRS destination “callsigns” to “destination addresses”. * Added TEL* to the list of generic destination addresses. * Added brief explanations of how several generic destination addresses are used. * Added “Grid-in-To-Address” (but marked as obsolete). * Extended the description of the Comment field, with pointers to what can appear in the field. * Added explanation of base 91. * Added paragraph on lack of consistency in on-air units, and default GNSS datum = WGS84. * APRS Data Type Identifiers Table: marked Shelter Data and Space Weather as reserved DTIs. marked the - DTI as unused (previously erroneously allocated to Killed Objects). marked the ' DTI to mean Current Mic-E data in Kenwood TM-D700 radios. marked the ‘ DTI as not used in Kenwood TM-D700 radios. * Position Ambiguity: need only be specified in the latitude — the longitude will have the same level of ambiguity. * Added the options of .../... and ˽˽˽/ ˽˽˽ to express unknown course/speed. * Added DFS parameter table. * Added Quality table for BRG/NRQ data. * Position, DF and Compressed Report formats: split the format diagrams into two parts (with and without timestamps). * DF Reports: added notes: BRG/NRQ data is only valid when the symbol is */*. CSE=000 means the DF station is fixed, CSE non-zero means the station is moving. * Compressed position reports: corrected the multiplication/division constants for encoding/ decoding. * Mic-E chapter rewritten and expanded. Emphasized the need to ensure that non-printing ASCII characters are not dropped. Corrected the Mic-E telemetry data format. * Expanded the introductory description of Objects/Items. All Objects must have a timestamp. * Added Area Object Extended Data field to Object and Item format diagrams. * Added Object/Item format diagrams with compressed location data. * Killed Objects/Items: now indicated by underscore after the name. (continued on the next page)
Date Doc Version Status / Major Changes
1.0.1m (continued) * Re-categorized weather reports: Raw, Positionless and Complete. * Added a statement that temperatures below zero are expressed as -01 to -99. * Added the options of ... and ˽˽˽ to express unknown weather parameter values. * Corrected the storm data format. Also, central pressure is now /ppppp (tenths of millibar). * Corrected the telemetry parameter data (now APRS messages instead of AX.25 UI beacons). * Added optional comment field to the Telemetry (T) format. * Added a section describing the handling of multiple message acknowledgements. * Added a section on NTS radiograms. * Added Bulletin/Announcement implementation recommendations. * Queries and Responses: Query Names (e.g. APRSD): all upper-case. A queried station need not respond if it has no relevant information to send. A queried station should ignore any query type that it does not recognize. APRSH: callsigns must be padded to 9 characters. * Added PING as a synonym of APRST. * Extended meteor scatter ERP beyond 810 watts, and added a lookup table. * Maidenhead Locator: all letters must be transmitted in upper case, but may be received in either upper or lower case. * Changed the definition of non-APRS packets — these are not APRS Status Messages, but may optionally be treated as such. * APRS Symbols chapter substantially rewritten.. * Added section on Symbol Precedence (where more than one symbol appears in an APRS packet). * Clarified some of the descriptions in the APRS Symbol Tables. * Added overlay capability to the \a symbol (ARES/RACES etc). * Separated the 7-bit ASCII table from the Dec/Hex (0x80-0xff) conversion table. * Added several new entries and a units conversion table to the Glossary. * Added new references to NMEA sentence formats and Maidenhead Locator formats.
Date Doc Version Status / Major Changes
29 Aug 2000 1.0.1 Protocol Version 1.0. Approved public release. Minor additions/changes to the draft 1.0.1m specification: * Added Foreword. * Replaced section on Map Views and Range Scale. * APRS Software Version No: added APDxxx (Linux aprsd server). * APRS Data Type Identifier: Designated [ as Maidenhead grid locator (but noted as obsolete). * Position Ambiguity: added a bounding box example. * Compressed Position Formats: for course/speed, corrected the range of possible values of the “c” byte to 0–89. * Mic-E: replaced the latitude example table, to show more explicitly how the N/S/E/W/Long offset bits are encoded. * Mic-E: removed the paragraph stating that there must be a space between the altitude and comment text — no space is required. * Mic-E: removed the note on inaccurate altitude data, as GPS Selective Availability has been switched off. * Object Reports: added timestamps to some of the examples (an Object Report must always have a timestamp). * Signposts: can be Objects or Items. * Storm Data: changed central pressure format to /pppp (i.e. to the nearest millibar/hPascal). * Storm Data: Hurricane Brenda examples: inserted a leading zero in the central pressure field (central pressure is 4 digits). * Telemetry Data: Added MIC as an alternative form of Sequence Number. MIC may or may not be followed by a comma. * Messages: added the reject message format. * Appendix 1: Agrelo format: changed the separator between Bearing and Quality to /. * Symbol Table: changed /( symbol from “Cloudy” to “Mobile Satellite Ground station”. * Reformatted the Units Conversion Table.
Date Doc Version Status / Major Changes
18 Feb 2024 1.1 Merged in updates from http://www.aprs.org/aprs11.html This copy of the APRS SPEC Addendum 1.1 was approved by the APRS-WG . (Vote was called 30 July 2004). This APRS1.1 page is always maintained current such as the SYMBOLS and TOCALLS links below. All new updates and additions to APRS since 2004 are found on the APRS 1.2 proposed draft addendum. APRS SPEC FINALIZED as of July 2004: This APRS Specification version 1.1 represents additions, corrections, and deletions since the original APRS1.0 spec of 21 June 2000. This edition represents the state of the APRS protocol and its usage through July 2004. As of this date, the state of the APRS users showed almost 27,000 stations worldwide of which: * 33% are fixed or home stations (includes WX stations) * 36% are infrastructure (30% digis and 6% IGates) * 31% are mobiles CORRECTIONS: * Page 18 X1J exception. Abandoned/deprecated in 2012. Now the ! DTI is only at the beginning. ✓ * Page 55 Mic-E Altitude. Optional altitude should be first after the Mic-E type byte. (type byte was extended in addendum 1.2) ✓ * Page 25 refers to a 'WPT' NMEA sentence type. Curt, WE7U assumes that should be 'WPL'? ✓ * The Antenna Gain in the PHG format on page 28 is in dBi. ✓ * Page 34 DF NRQ is not defined in spec. See original DF.TXT and PROTOCOL.TXT ✓ * Page 45, We now avoid the term "Mic-E Messages" and use the term "Mic-E Position Comment" for these bits. ✓ * Page 48, 100-109 goes to "u" instead of DEL and 110-179 is 38-107 going to "k" instead of DEL. ✓ * AX-25 Table: The AX-25 UI-Frame TABLE lists Flags at the end of a packet being 2 bytes. . . The correct number is 1, and it may be shared with the next packet. (From VK2TDS). ✓ * Default Paths of WIDE2-2, not RELAY or WIDE. (page 11) (updated June 2006) ✓ * Normally, HID should be OFF in all APRS TNC's (page 91). ✓ * SSID Conventions in user calls (page 95) ✓ * DATUM: Standard is WGS-84, but Continental options such as OSG for the UK are OK.(page 21) See !DAO! concept in APRS1.2 ✓ * Range Scale: The standard view size descriptor for APRS displays. ( map example ). (page 11) ✓ * Time Stamps on receipt (page 23). ✓ SYMBOL UPDATES: * See all about Symbols! ✓ * SSID Conventions for quick visual identification ✓ * Updated SYMBOL tables. . But see also all the APRS1.2 proposals for new Symbol Extensions ✓ * Overlayable Symbols subset. . These were always defined as overlays in the original APRS. ✓ * Upgrading your symbol set gives background on fixing up your symbol set. ✓ * JUST MOBILE PRIMARY SYMBOLS: !'<=>()*0CFOPRSUXY[\^abefgjkpsuv <== [added !F\ ] ✓ * JUST MOBILE ALTERNATE SYMBOLS: >KOS^ksuv <==[removed /0An] ✓ * JUST WEATHER PRIMARY SYMBOLS: _ and W ✓ * JUST WEATHER ALTERNATE SYMBOLS: ([*:<@BDEFGHIJTUW_efgptwy{ ✓ * Timeout Old Stations (fade-to-gray). Now 80 mins instead of 2 hrs to account for stations via satellites (page 10). ✓ * Symbol Attributes for map displays. (page 92) And Position Ambiguity (p-24) ✓ * DIGI Overlay Characters (new for page 11) ✓ * Have PHG Range Circles to account for real-world PHG range due to multipath & fading. ✓ (page 29) See all about PHG ✓ * New WAYPOINT symbol: Red dot (with overlay) marks a mobile's destination. Drawn with a line between the mobile and its waypoint destination. ✓ OBJECT (and NAME) CLARIFICATIONS: * Name/Call equality and SPACES-in-names Manifesto ✓ * OBJECTS: Amplifying comments on ownership, killing and equality with stations.(page58) ✓ * OBJECT names should not have any punctuation that cannot be converted to valid Wapoints on most GNSSs. That would depend on GNSS Vendor. Where is this defined? 🗴 * AREA Objects are poorly described in the spec. (page 60) ✓ * Polygon and Line OBJECTS (new for page 31) Link is now longer valid. Same information is now at More Information about APRS NSW Weather can be found at https://www.aprs-is.net/wx/ ✓ * Compressed Objects: not recommended for use on RF due to incompatibilities (page 58) For 1 foot precision, use $GPGGA, or 3rd party compressed posits, or the proposed !DAO! format. ✓ * ITEM Format is not recommended on RF due to incompatibilities (page 37) ✓ UPDATED TABLES and INFO: * WB2OSZ description of SSID - C bits ✓ * TO-CALLS and Version ID's updated (page 14) ✓ * Experimental Formats (page 89) ✓ WEATHER RELATED ISSUES: * Raw Weather Formats not recommended. Microprocessors should convert to complete format on RF (pg 62) ✓ * Weather Details. Amplifying comments on the original spec 1.0. (page 64) ✓ * The WXSVR Protocols managed by Dale Hugley. See example. See description: MOBILE.TXT. ✓ * APRS-IS (Internet System): ✓ * NOGATE and RFONLY in the RF DIGI field should not be forwarded into the APRS-IS by IGates. ✓ * !x! means no archive. Any packet containing this string should not be archived by any of the APRS-IS data bases. Positions, status or messages. ✓ * APRS-IS Core and Tier-2 servers web pages and how they work. ✓ * The q-construct: Marks the source of entry of all packets into the APRS-IS. ✓ (Referred reader to the APRS-IS documentation.) * IGATE Status Report Format: Left_bracket then "IGate, MSG_CNT=N, LOC_CNT=N" ✓ APRS 1.1 SPEC Operating Conventions for the Good of the APRS Network: * The New-N Paradigm obsoleted old RELAY and WIDE and TRACE for 300-500% network improvement ✓ * APRS Voice-Alert for instant voice contact with any APRS mobile * Reply-ACKS Algorithm: Really makes message QSO's FLY! (page 73) ✓ * Recommended DIGI paths and striving for network protection ahead of too much user flexibility. ✓ * Digipeater ID rates for optimum APRS networks ✓ * Auto-Answer messages are SPAM to the network in most cases. To limit their impact, all original APRS clients adhered to these rules for auto-answer messages: 1) Any such AA message text should begin with AA: 2) Any such AA message should not have a Line number (so it does not cause acks) 3) Any such AA message is only sent once on each incoming message packet (no forced retries) 4) Any such AA message should default to OFF on power up. 5) Any such AA message should be canceled when the client detects the return presence of the operator 6) Any such AA message can be ended with a }yy REPLY-ACK if the software supports it. Auto-Answer seems to be a Kenwood invention. It does not belong here but we should start compiling a list of non-standard extensions. 🗴 The above is the complete APRS 1.1 Spec Addendum. It was a compilation of all the accumulated feedback from users and authors about errata, errors, typos and any omissions in the spec that had been accumulated from the time of the original spec to June 2004. This APRS errata page had been running continuously for years and was updated whenever these items were discovered and each of these items were widely published and discussed on the APRSSIG and the APRSSPEC working group for public discussion. But it was decided best to finally Freeze the accumulation in June 2004 as APRS1.1 and then after public posting approve it. Then to begin working on any new issues as APRS1.2.
Date Doc Version Status / Major Changes
18 Feb 2024 1.2 1.2b 1.2c Merged in updates from http://www.aprs.org/aprs12.html APRS 1.2 SPEC ADDENDUM PROPOSALS: The APRS protocol was well defined by the 1996 time frame in the original APRSdos docs. But it was then formalized in the APRS1.01 publication in 2000. The first APRS 1.1 ADDENDUM was completed and approved in July 2004. . This APRS1.2 addendum contains all the spec updates since then. . For a comparison of what has been implemented in what clients, please see the Capabilities Chart. But first we will list as a reminder all of those items that have already been included in 1.1: Editor’s Note: Addendum 1.2 is much different than 1.1. Much of it is redundant, recapping what was in 1.1, or “…ideas that have been proposed for further discussion and eventual adoption …” I’ve tried to select only the actual specification additions which have been implemented. SPEC ADDITIONS: * Proposal (28 Apr 2020): Allowing 000-999 in addition to the original 000-255 telemetry fields in the five channel T#sss,111,222,333,444,555... format. ✓ * PHG in Mic-E format. The Mic-E text field can contain any normal Position comment field too. Such as PHG. (important for Mic-E hardware digipeaters). ✓ * Original Mic-E Telemetry Format is deprecated. Overtaken by MFR TYPE codes. A new Telemetry format has been developed See spec . ✓ * High precision !DAO! & datum option with precision to 1 ft with included datum. ✓ * Adding Frequency to packets Lets you find someone in the Freq domain! ✓ * New UTF-8 text encoding and decoding where possible. ✓ * Voice Frequency Format for including operating frequency in APRS. see spec. ✓ * Mic-E TYPE Codes for different capabilities. See a set of Mic-E Examples!. ✓ * Probes (PHGR) addition to PHG for real-time measuring of Network Reliability. ✓ * Explain p-persistent CSMA for channel access. This was probably not in the original because everyone was using legacy TNCs at the time and the TNC took care of it. * Changed GPS to GNSS because there are now other similar systems. * Barometric pressure field should be a total of 6 characters, not 5. * Overhauled Third-Party Packet section. * Add metric units to PHG table.