
            Using the Wisconsin Network - Part 37
                 by Andy Nemec, KB9ALN

     In our last discussion concerning Internet Gateways, we
started a discussion of mail service. This time out, we will
continue our discussion as there is a lot more to internet
E-Mail than there is to most packet mail. In our examples, we
have been using a typical gateway setup, KB9BYQ's TNOS gateway
in Appleton. He has a special arrangement with N9RJZ in
Appleton, John provides the Internet service that Al's Gateway
uses. 

     Internet E-Mail, as most often seen, is "plain text". That
is, a letter typewritten and easily readable as ASCII text. Of
course, as soon as people found out how wonderful electronic
mail was, they wondered if it was possible to mail programs,
pictures, and other binary format files. Of course it is,
through the use of encoding and the E-Mail attachment.

     You can send someone almost any kind of file in this
manner, a binary executable program, a JPG picture, and even
video and "movies". You can also send word processor and other
files ("rich text") that are stored in a binary format. These
are exactly the same as any other binary file, therefore, they
must be specially encoded to be sent in a "plain text" mode.

     If you operate a TCP/IP station, you probably already know
that the mailer you use will take care of any special file
types (at least most often). The information provided below is
not so much for you, but for users who connect via AX.25 text
mode to collect their mail from the gateway. Most TCP/IP users
will have their mail automatically collected by your TCP/IP
program. However, you may find the following information
helpful, especially the information concerning file sizes.

     There are various methods used to encode programs so that
they can be mailed, among them UU, Base 64 and Bin2Hex. While
this is no problem for the internet, where data rates reach
astronomical speeds, they can represent a considerable
challenge when collected by packet radio. There are a few
things to consider if you decide to mail or receive a program
encoded in this manner.

     The first thing to consider is the size of the file.
It would be a lifelong endeavor to collect a 1-megabyte file at
1200 bps! You best recommend to anyone mailing you at a gateway
to limit file sizes. Even a 10K file can try your patience at a
typical LAN speed.

     Also remember that sometimes an encoding program will
double the size of the file! Before you send anything this way,
encode the file and look at the file size. Anything that
"bloats" a file is to be avoided (unless the file is a small
one).

     In order for a lot of word-processor documents to be
successfully transferred, you may need to convert these as well.
Most of these kinds of files are a combination of plain text as
well as odd control characters. In order for them to be safely 
transferred, they should be encoded prior to being sent.

     HTML documents, on the other hand, do well via standard
packet mail. HTML is a text-based programming language that is
used extensively on the World-Wide Web. Of course any such
document must be viewed with a Web Browser, but they can be
transferred via packet mail, with no encoding necessary.

     How to tell if you need to encode a file? That's pretty
easy. If it has a file extension of .TXT, then it is usually
safe to send without encoding. Don't be fooled by a .DOC
extension - most of these are plain text, but some are word
processor documents containing formatting and control
characters. When in doubt, look at it with the DOS "TYPE"
command (or a program like LIST.COM) and look for odd
characters on the screen, or beeps coming from your PC's
speaker. If you see or hear anything unusual, then it should be
encoded. Any document created with a word processor and not
saved as "ASCII plain text" will need to be encoded.

     That being said, here's a special warning to users of
Windows "Write!". Even if you tell this program to save the
file in "plain ASCII text", it will add extraneous control
characters to the file. Take note of this and either use a
plain text editor, or use a different word processor that you
are certain saves files as plain text.

     Now that we have a pretty good idea of what might need to
be encoded, we should explore what kinds of encoding and
decoding program can be used. One of the more popular ones used
by Internet mailing programs is base 64. The procedure in a
case like this is to capture the file as you would any other
text file you are saving. Then copy the file to the directory
that your internet mailer uses, and tell it to decode it. Then
you look at it with the mailer, or save the executable file you
have been sent.

     Another method of file transfer via mailing is to use the
UU encode and decode programs. These are stand-alone DOS
programs that will encode or decode a binary-format file into a
format that looks like plain text to the mail programs. When
receiving a file like this, simply tell the UUDECODE program to
decode it. You can then use the executable, or view a "rich
text" format message or word processor document. 

     Either of these file conversion methods are likely to be
decodeable by mailers, or at least easily decodeable with a
stand-alone program. When in doubt about any such file
exchange, think about the following:

 -    Will your correspondent be able to decode the message?
 -    Will you be able to decode the message?
 -    How big is the file? Common sense says to keep any file
      under about 10K.
 -    What is the content of the file? Remember, a picture file
      of inappropriate subject matter is just as illegal as any
      illegal wording.

     And one more thing to discuss. Many of you have seen me
use words like "Encode" and "Decode". Many astute observers will
wonder if encoding a message sent via packet is legal. The
phrase "Codes and Ciphers" in part 97 rings a bell with most
people, but they often forget the "rest of the story". The full
text of the rule in question should help to reassure you on
this matter.

     This rule points to intent of the encoding more than anything
else. Remember, it is illegal to code a message to hide it's
meaning. It is OK to compress or encode a message if the intent
of the encoding is to facilitate message exchange. In other
words, if you are using encoding to make a message transfer
more efficient or even just plain possible, you are following
the law. If you are using encoding simply to make it harder for
someone to see your message, then you are outside of the law.

     That's all for this time. In the next part of our series,
we will continue to discover more of the features of the gateway.
Until then, 73 from Andy.
