# [erlang-questions] Erlang external binary term format

Kenneth Lundin kenneth.lundin@REDACTED
Mon Oct 6 12:56:58 CEST 2008

```You find the documentation of the Erlang external term format here:
http://www.erlang.org/doc/apps/erts/erl_ext_dist.html#8

(It is chapter 8 of the ERTS Users Guide)

/Kenneth Erlang/OTP tema, Ericsson

On Mon, Oct 6, 2008 at 3:29 AM, deepblue_other <cktgatb@REDACTED> wrote:
>
> for example
> one day I was looking at the term_to_binary() output of
> {binaries,"are",useful}
> and it was:
> 131,104,3,100,0,8,98,105,110,97,114,105,101,115,107,0,3,97,114,101,100,0,6,117,115,101,102,117,108
>
> so with a little experimentation with other tuples I got these rules so far:
> 131,104       - this means that its a tuple
> 3                - this means that it has 3 terms
> 100 and 107 - type code - in this case 100 stands for atoms, and 107 stands
> for strings
> 0                - is the separator between the "type code"(name I gave it
> just now ;) ) and the actual ASCII sequence
> 8 and 3(again) and 6 - these indicate the length of the binary sequence
> (number of ASCII characters in this case
>
> so:
> binaries - 100(type code),0,8(byte length),98,105,110,97,114,105,101,115
> "are"     - 107(type code),0,3(byte length),97,114,101
> useful   - 100(type code),0,6(byte length),117,115,101,102,117,108
>
> this just explains a limited set, doesnt go into lists...
> I could be wrong, but the rules seem to match up other examples as well
>
> thanks
>
> deepblue_other wrote:
>>
>> term_to_binary() outputs a binary.
>> what is the format of that binary? I would like to create a
>> "unpacker/packer" for that format in ActionScript3, and avoid the use of
>> XML (which Im using now for Flash-to-Erlang) communication altogether. it
>> would be faster, less code, and much more efficient from the bandwidth
>> point of view.
>>
>> is there a document someplace that gives the byte layout maybe?
>> thank you
>>
>
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```