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-# Postcard protocol, version 1
-
-The POSTCARD PROTOCOL is a federated asynchronous communication protocol that
-aims to simulate the experience of sending postcards through the physical mail
-online.  A NETWORK consists of a series of servers, known as POST OFFICES, which
-provide a limited number of user accounts (P.O. BOXES) that can send and receive
-short messages, called POSTCARDS.  The protocol is implemented on top of UDP and
-tries to be relatively secure and mitigative against abuse.
-
-The postcard protocol is in ALPHA status and may change while we're working
-toward a version 1.0.  Below, each part of the protocol is described.
-
-## POSTCARD.
-
-A POSTCARD is a datagram that fits within a single UDP packet.  While the
-*actual* limit to UDP packet size is 2^16 bits[1], the number I've seen around
-the internet for a *safe* UDP packet size is more like 512 bytes.  So that's
-what we're going with --- especially because a physical postcard is much closer
-in data size to 512 bytes than 2^16 or even 1500 (another limit mentioned in
-Julia Evans's blog referenced above).
-
-A POSTCARD's size is further restricted (though not by much) by a short header
-with the following fields:
-
-* 2b MAGIC NUMBER: the ASCII codepoints of the letters "PC" (for postcard)
-* 1b VERSION: The version of the postcard protocol being used
-* 1b ENCODING: The text encoding of the postcard's message (see Appendix A)
-* 1b TOBOX: The P.O. BOX of the message recipient
-* 1b FROMBOX: The P.O. BOX of the message sender
-
-This header is 6 bytes long, leaving 506 bytes for message text:
-
-```
-,___________________________________________________________________.
-|________________ POSTCARD PROTOCOL DATAGRAM SKETCH ________________|
-> "PC" (2 bytes) |version,encoding|to(1b)  from(1b)|message(506b)   |
-|0101000001000011|0000000100000000|ttttttttffffffff| . . . . . . . .|
-^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-```
-
-## P.O. BOX.
-
-## POST OFFICE.
-
-## NETWORK.
-
-### APPENDIX A. Encoding table.
-
-While UTF-8 is the answer for almost every question of encoding in the modern
-day, on a byte-restricted format like the postcard protocol I think it's unfair
-for non-English speakers to be forced to use double or even triple the bytes to
-send the same message.  Therefore, the ENCODING field of a postcard's metadata
-corresponds to the message encoding, which allows senders to choose a more
-storage-friendly encoding for their messages.
-
-ENCODING is stored as a 1-byte number, allowing for 256 possible encodings.  As
-of Postcard protocol v. 1, these are recognized:
-
-``` | table
-0       UTF-8
-1       ASCII
-2       EBCDIC
-3       ISO 8859-1 Western Europe
-4       ISO 8859-2 Western and Central Europe
-5       ISO 8859-3 Western Europe and South European
-6       ISO 8859-4 Western Europe and Baltic countries
-7       ISO 8859-5 Cyrillic alphabet
-8       ISO 8859-6 Arabic
-9       ISO 8859-7 Greek
-10      ISO 8859-8 Hebrew
-11      ISO 8859-9 Western Europe with amended Turkish character set
-12      ISO 8859-10 Western Europe with rationalized Nordic character set
-13      ISO 8859-11 Thai
-14      ISO 8859-13 Baltic languages plus Polish
-15      ISO 8859-14 Celtic languages
-16      ISO 8859-15 ISO 8859-1 with rationalizations
-17      ISO 8859-16 Central, Eastern and Southern European languages
-18      CP437
-19      CP720
-20      CP737
-21      CP850
-22      CP852
-23      CP855
-24      CP857
-25      CP858
-26      CP860
-27      CP861
-28      CP862
-29      CP863
-30      CP865
-31      CP866
-32      CP869
-33      CP872
-34      Windows-1250 for Central European languages that use Latin script
-35      Windows-1251 for Cyrillic alphabets
-36      Windows-1252 for Western languages
-37      Windows-1253 for Greek
-38      Windows-1254 for Turkish
-39      Windows-1255 for Hebrew
-40      Windows-1256 for Arabic
-41      Windows-1257 for Baltic languages
-42      Windows-1258 for Vietnamese
-43      Mac OS Roman
-44      KOI8-R
-45      KOI8-U
-46      KOI7
-47      MIK
-48      ISCII
-49      TSCII
-50      VISCII
-51      Shift JIS
-52      EUC-JP
-53      ISO-2022-JP
-54      JIS X 0213
-55      Shift_JIS-2004
-56      EUC-JIS-2004
-57      ISO-2022-JP-2004
-58      GB 2312
-59      GBK (Microsoft Code page 936)
-60      GB 18030
-61      Taiwan Big5 (a more famous variant is Microsoft Code page 950)
-62      Hong Kong HKSCS
-63      Korean
-64      EUC-KR
-65      ISO-2022-KR
-```
-
-This list is pulled from Wikipedia's entry on common character encodings[2], so
-it may need to be revised.
-
-## END NOTES.
-
-=> https://jvns.ca/blog/2017/02/07/mtu/ [1]: J. Evans. "How big can a packet get?"
-=> https://en.wikipedia.org/wiki/Character_encoding#Common_character_encodings [2]: Wikipedia.  "Character encoding"