More that you ever wanted to know about international standards ISO 11784 and ISO 11785 regarding animal identification transponders:

If you read the web for information about the two international standards ISO 11784 and ISO 11785 you may learn things like: 1. ISO 11784 describes the chip/transponder and ISO 11785 describes the scanner/reader. 2. They specify a transponder with an ID code that is 15 digits long. 3. They specify, among other things, a transponder type called "FDX-A" and a transponder type called "FDX-B". 4. They describe more than one type of transponder commonly used for pets, and all are described "as compliant" to the standard. 5. Chips marketed in the US under names such as AVID EUROChip or HomeAgain operate as described in an ISO 11785 Annex. 6. ISO 11784 and ISO 11785 are open standards. But are any of these statements really true? Here are my comments.

Is it true as some sources state that ISO 11784 describes the chip/transponder and ISO 11785 describes the scanner/reader? No. ISO 11785 describes protocols to be used by transponders and readers (which it calls "transceivers") and gives some details about their construction. ISO 11784 only tells how the 64-bit identification code stored on transponders in conformance to ISO 11785 is to be built up. There are 38 bits for the main identification code, to be a "Unique number within a country," 10 bits for a country code, and a one-bit flag to indicate if an additional block of data, such as "physiological data," is provided. (Not currently common in pet applications.) Then there are 14 bits left as "reserved," at least in the current August 1996 edition, and there's one bit to indicate whether the transponder is for an animal application or non-animal. (No guidance is given as to whether human beings are animals...) That's the order of transmission of the bit fields; the numeric values are transmitted "Least Significant Bit first" according to ISO 11785. For the country code field, codes 900 through 998 "may be used" to refer to individual manufacturers. These commonly are seen in transponders in pets. Country code 999 indicates a "test transponder" whose number may not be unique. In all cases the standard still calls it a country code.

But is it true that the ISO standards specify a transponder with an ID code that is 15 digits long? Maybe. Well, the 38 bit field expressed as a decimal number gives a value from 0 to 274877906943, so that's 12 digits right there. The 10 bit country code field has values from 0 through 1023 giving 4 digits. The country code according to ISO 11784 is an "ISO 3166 numeric-3 country code" which you might assume should only take 3 digits, but right next to that description is the legend that the number of combinations is 1024. I don't see any definite statement in ISO 11784 or ISO 11785 that a country code can not be in the range 1000 to 1023; so although it may be unlikely that these codes will be used for any transponders, a reader should probably accommodate them, meaning 16 decimal digits total. But even if you assume that only country codes up to 999 need to be supported, there's nothing in the standard to support combining the two decimal numbers to make one long number. If there was, there would have to be an instruction telling whether to put the Country Code first or last. That instruction isn't there. You might say that putting the Country Code first, as is commonly done, is the obvious order, but that's not the order the transponder transmits them in. The Max Microchip software prints the full 4 digits for the Country Code, and puts a separating space character between that and the 12 digit part.

And is it true that the ISO standards specify a transponder type called "FDX-A" and a transponder type called "FDX-B"? I've looked carefully, and the only place I see anything like this is one mention of "FDX B technology" in the Introduction section of ISO 11785. It is used without any dash or hyphen, and it appears in the context of talking about patents held by one specific company. I don't see FDX-A or FDX-B used to describe any of the transponder types or protocols, old or new, that are detailed in the ISO 11785 main body or any of its annexes. And these terms don't appear in the definitions section or the table of Abbreviations. So the Max Microchip unit doesn't use these descriptions. Actually it would have made a lot of sense for the standard to give the protocols names like FDX-A, FDX-B, FDX-C, and FDX-D, but it doesn't.

Some sources claim that the ISO standards describe more than one type of transponder commonly used for pets, and all are described "as compliant" to the standard. Is this true? When I look at ISO 11785, I see the protocols of five transponder types described in the standard. Section 6.1 describes a "Full duplex system" protocol which is now widely used for pets around the world. Section 6.2 describes a "Half duplex system" which is usually implemented in relatively large implantable chips or ear tags for livestock. These are not likely to be found in pets unless you include, for example, a pet cow or pet elephant. Then there are three more types listed in Annex A. Section A.2.1 describes a "Destron (FECAVA version) technology" type, with 35 information bits; section A.2.2 describes a "Datamars technology" type, with 48 information bits; and section A.2.3 describes a "Trovan technology" type, with 39 information bits. (These are the names given in the paragraph headings, and it sure would be nice if shorter names were given.) But does this mean we can have 5 types of compliant transponder? It might seem so, since there is a statement in the Foreword on page ii of the standard that says "Annexes A and B form an integral part of this International Standard." But section 2 on "Conformance" doesn't support 5 compliant types. It says "Transponders are in conformance with this International Standard provided they meet the requirements given in clause 6 of this International Standard." So at least if "compliant" means the same thing as "in conformance," there are only two kinds of transceivers that are compliant. So why are the three types described in the Annex included at all? Section 2 makes that clear also. It's because Transceivers (readers/scanners) may need to read them, at least for a period of time. ISO 11785 describes 5 types of transponders, all of which may be readable on a fully capable reader, but only two of which are themselves in conformance to the standard. The other three, although they were never in conformance, are and will always be, described in ISO 11785. The Max Microchip reader makes use of the appropriate paragraph headings from ISO 11785 as authoritative names for the protocols that it decodes following descriptions in the standard.

I've also seen it claimed that transponders marketed in the US under names such as AVID EUROChip or HomeAgain operate as described in Annex A. From the limited specimens I've seen of these types, I found this not to be true. They show up as described for chips of the "Destron (FECAVA version) technology" type, except completely backwards. The "Destron (FECAVA version) technology" type calls for use of Frequency-Shift-Keying, meaning the information is encoded by two specific frequencies in the detected signal. I found my specimens, one each EUROChip and HomeAgain, put out a High (frequency) when the standard calls for a Low, and a Low when it calls for a High. So the Max Microchip reader will report these as "Inv. ISO 11785 A.2.1" type transponders, where the "Inv." stands for inverted.

And for a final question, are ISO 11784 and ISO 11785 open standards? Not in the sense of the Open Standards the Internet was built on. I paid 90 bucks at for my copies of ISO 11784 and ISO 11785; they may be slightly cheaper directly from the ISO's site depending on the Swiss Franc exchange rate at the time. With a true open standard, like my own rec.pets-2005a, you can reasonably assume that at least some of the people you read talking about it on the 'net, have actually read the document.

There's one more sloppy thing about the ISO standards to discuss. In the three protocol descriptions in Annex A, they don't say how to convert the binary coded information bits into a printable number. A direct conversion to a decimal number representation might be inferred as reasonable, but in the case of the 39-bit "Trovan technology" type, the code numbers I received with my specimens were Base-16 hexadecimal, so I adopted this convention for that chip type. In the case of the 35-bit "Destron (FECAVA version) technology" type, the code numbers I received with my specimens looked like Base-16 hexadecimal, but on closer observation, each of them when interpreted as standard Base-16 gave a bigger number that the largest possible 35-bit binary number. To make the numbers match, I had to use a rather odd conversion method, where each 7-bit piece of the 35 bit binary number is converted to a two-digit Base-16 hexadecimal representation, for a total of 10 characters in the result. The Max Microchip reader uses this convention for both Inverted and coded-per-standard variations of 35-bit types, although as I said, I haven't found a specimen that was coded-per-standard; indeed they may not exist at all.

For the current version of the Max Microchip design, the "Half duplex system" type chips are not supported, and they may never be. The "Datamars technology" type is not currently supported; I couldn't get specimen chips. These two types are uncommon in the U.S. pet population. Support for "Trovan technology" type chips should be considered as experimental quality at best; the Max Microchip machine's simple hardware is not well suited for the signal they transmit. (Not many U.S. pets have these either.) When detected, they may produce output like this:

ISO 11785 A.2.3 "Trovan technology": 0001EF44C1                        (127260)
ISO 11785 A.2.3 "Trovan technology": 0001BE32F8                        (127137)

Here the numbers in parentheses are an estimate of the excitation frequency. This estimate is made from analyzing the timing of the waveform transmitted by the transponder. Now here's an example of the output produced by an AVID EUROChip and a HomeAgain transponder:

Inv. ISO 11785 A.2.1 "Destron (FECAVA version) technology": 136215372A (126037)
Inv. ISO 11785 A.2.1 "Destron (FECAVA version) technology": 46781B102A (126265)

Again, the "Inv." notation indicates a transmission that decodes as inverted or backwards from the description in ISO 11785 Annex A. If you ever see a transponder that reads without the "Inv.", like this:

ISO 11785 A.2.1 "Destron (FECAVA version) technology": 0001234567      (126113)

I'd like to hear about it. I would theorize that the original "Destron" specification is incorrectly represented in the ISO standard. As long as that original specification is not in the public realm, however, the ISO's version is the only authority on what is correct and what is backwards. I wrote to Digital Angel Corp., which apparently is the the new name of the original Destron, asking for their original standard, but received no reply.

Note that the terms such as "Trovan", "Destron", and "FECAVA" which appear in the output from the Max Microchip reader are not an indication that specifications from the Trovan and Destron companies, or from the "Federation of European Companion Animal Veterinary Associations", have been used in the decoding. These terms are used only as part of the ISO 11785 paragraph headings which are applicable to the waveform received. These names are unwieldy, but as exact paragraph headings, they are the most correct and precise names for the protocols that I could pull out of ISO 11785, which is the most authoritative reference available. If I didn't want to be precise, I might just have it print the code number and be done with it.

Finally, for the case of actual ISO conformant transponders, you may see something like this:

ISO 11785 6.1 "Full duplex system": 0985 120027629061           (1,8000,126071)
ISO 11785 6.1 "Full duplex system": 0985 120028223912           (1,8000,126071)

For these, there is additional information in the parentheses on the right. Here the "1" is the animal/non-animal bit, where "1" = "animal". And between that and the frequency estimate is a Base-16 hexadecimal representation of all 16 leftover bits (the 14 Reserved bits and 2 Flags) from the chip's 64-bit code data, after the 48 bits used for the Country Code and main ID number are removed. The animal/non-animal bit appears again as the most significant bit of this code.

In all cases, the limited amount of space available in an 80-character output line precluded including a clarification of which of the detected transponder types are in conformance to ISO 11785, and which are only described in ISO 11785.

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