Encoding and Decoding: Overview and List of Third-Party Vendors |
Q179323
The information in this article applies to:
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Apple Macintosh System Software, versions 7.0, 7.0.1, 7.1, 7.5, 7.5.1, 7.5.2, 7.5.3, 7.5.5, 7.6, 7.6.1, 8.0
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Microsoft Windows 95
SUMMARY
This article includes the following information:
- A brief history of file encoding
- A list of encoding guidelines
- A list of third-party manufacturers of encoding and decoding utilities
A BRIEF HISTORY OF ENCODING
Uuencoding
This was historically the first method invented. The encoding was quite
simple and caused frequent problems. In particular, the first
implementation used the space character for encoding. But, some mail
gateways stripped spaces at the end of a line; so, what the recipient got
was invalid. Later, a special case was introduced to avoid this problem.
Xxencoding
This rarely used method appeared after the initial problems with
uuencoding, but before they were fixed. It avoids using the space character
by using a different character set for encoding.
Base64
This method was introduced for Multipurpose Internet Mail Extensions (MIME)
standard, avoiding some rarely encountered problems with the other two
methods (which used some characters not available on some computers).
Together, with other benefits of MIME, this is the most secure method.
BinHex
A method conceived for transferring files among Macintosh systems. Files on
a Macintosh consist of two parts, the "data fork" and the "resource fork."
This encoding first adds a third header part, and composes the three parts
into a single data stream, which is then slightly compressed and encoded.
ENCODING GUIDELINES
When you work with file encoding, follow these guidelines:
- Avoid Xxencoding, which is obsolete.
- You must use BinHex for Macintosh systems. It should not be used on
other systems, because decoders are not widespread elsewhere.
- If your mail software is MIME-compliant and offers to "attach" files
encoded in Base64, use this method of encoding, as it is the preferred
method for MIME messages. Otherwise, use uuencoding, which is still the
most common encoding method.
NOTES:
- MIME-compliance is something only the mail software can handle. For
example if you encode data to Base64 using UUDeview and then include
the encoded data in your message, the resulting message will not be
MIME-compliant.
- If your mail software does not allow "attachments" on its own and you
have to use an external encoder, always use uuencoding.
- Software is becoming more and more MIME-compliant which means that
the uuencoding method will be replaced by Base64. However, as long as
there is the possibility that the recipient uses older software,
uuencoding is the safest method.
- Compression is also an important issue. When possible, you should send a
file compressed into a ZIP file or some similar format.
THIRD-PARTY ENCODING AND DECODING UTILITIES
The following third-party utilities can reintegrate a text-encoded file
into its binary format:
MORE INFORMATION
The third-party contact information included in this article is provided to
help you find the technical support you need. This contact information is
subject to change without notice. Microsoft in no way guarantees the
accuracy of this third-party contact information.
The third-party products discussed here are manufactured by vendors
independent of Microsoft; we make no warranty, implied or otherwise,
regarding these products' performance or reliability.
Additional query words:
bin-hex hexadecimal