Internet DRAFT - draft-eberle-sdt
draft-eberle-sdt
Internet Draft J. Eberle
<draft-eberle-sdt-00.txt> FastnLight
Category: Informational
Expires: June 2007 December 2006
Standard Data Types
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Copyright Notice
Copyright (C) The Internet Society, December 2006.
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Internet Draft Standard Data Types December 2006
Abstract
This document assigns 25 common data types clear, unambiguous names, and
numerical identifiers. It also defines context dependencies, such as
byte-order and charset, to the data types, where necessary.
1. Introduction
This document attempts to codify a set of common data types, giving each
a clear, unambiguous name, and a fixed identifier. The names and
identifiers are designed to serve as the basis for higher-level data
typing constructs. On their own, the data type names serve to
streamline and sharpen technical writing.
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2. Type Catalog
ID Name Coding Bits Domain Context
-- ------- --------------- ---- --------------- -------------------
1 uint1 unsigned integer 1 0 .. 1
2 uint2 unsigned integer 2 0 .. 3
3 uint3 unsigned integer 3 0 .. 7
4 uint4 unsigned integer 4 0 .. 15
5 uint5 unsigned integer 5 0 .. 31
6 uint6 unsigned integer 6 0 .. 63
7 uint7 unsigned integer 7 0 .. 127
-- ------- --------------- ---- --------------- -------------------
8 uint8 unsigned integer 8 0 .. 255
9 uint16 unsigned integer 16 0 .. 65535 byte-order
10 uint32 unsigned integer 32 0 .. 2^32-1 byte-order
11 uint64 unsigned integer 64 0 .. 2^64-1 byte-order
-- ------- --------------- ---- --------------- -------------------
12 sint8 signed integer 8 -128 .. 127
13 sint16 signed integer 16 -32768 .. 32767 byte-order
14 sint32 signed integer 32 -2^31 .. 2^31-1 byte-order
15 sint64 signed integer 64 -2^63 .. 2^63-1 byte-order
-- ------- --------------- ---- --------------- -------------------
16 float32 floating point 32 +-10^ +-38 byte-order
17 float64 floating point 64 +-10^+-308 byte-order
-- ------- --------------- ---- --------------- -------------------
18 char8 character 8 256 codepoints charset
19 char16 character 16 65536 codepoints charset, byte-order
20 char32 character 32 2^32 codepoints charset, byte-order
-- ------- --------------- ---- --------------- -------------------
21 mb8 multi-byte char 8-32 2^30 codepoints charset
22 mb16 multi-byte char 16-32 2^31 codepoints charset, byte-order
-- ------- --------------- ---- --------------- -------------------
23 bcd4 binary-coded dec 4 0 .. 9, +, -
24 bcd8 binary-coded dec 8 0 .. 9, +, - charset
-- ------- --------------- ---- --------------- -------------------
25 void 0 {}
-- ------- --------------- ---- --------------- -------------------
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3. Type Details
3.1. Unsigned Integer (uint1, uint2, uint3, uint4, uint5, uint6, uint7,
uint8, uint16, uint32, uint64)
Representation: Base-2 positional, unsigned.
3.2. Signed Integer (sint8, sint16, sint32, sint64)
Representation: Base-2 positional, two's complement.
3.3. Floating Point (float32, float64)
Representation: [IEEE754].
3.4. Character (char8, char16, char32)
Representation: Base-2 positional, unsigned. Reference to codepoint
within charset selected by context.
3.5. Multi-Byte Character (mb8, mb16)
Representation: Depends on selected charset. Type mb8 can be used
with UTF-7 and UTF-8. Type mb16 can be used with UTF-16. Other
multi-byte charsets are handled in a similar manner.
3.6. Binary-Coded Decimal (bcd4, bcd8)
Representation bcd4:
{0000..1001, 1100, 1101} => {0..9, +, -}
All others undefined
Representation bcd8:
Depends on selected charset (ASCII family or EBCDIC family)
{'0'..'9', '+', '-'} => {0..9, +, -}
All others undefined
3.7. Void (void)
Representation: N/A.
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4. Context Details
A data type is not valid until all of its references to the context
have been established. For example, uint32 requires the byte-order
from the context. Likewise, char8 requires the charset from the
context.
There are many ways to establish context values. They can be written
to a file header, negotiated at runtime, specified in an architecture
document, etc. This document does not specify the mechanism. It
only defines the various dependencies.
4.1. Byte-Order
Byte-order is the order in which to store a series of bytes. It can
either be most-to-least significant, or least-to-most significant.
The former is called big-endian, the latter is called little-endian.
4.2. Charset
The charset defines the set of codepoints that a given character
value can point to. The set of valid charsets is defined in the IANA
Charset MIB file [RFC3808].
Note, not all charsets can be used with all character data types.
For example, charset ISO-10646-UCS-2 cannot be used with type char8.
Therefore, the user of these types must make informed charset/data
type pairings.
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5. Security Considerations
This document contains no security considerations.
6. IANA Considerations
The author recommends that the IANA create a registry to record the
data type names and identifiers described in this document.
7. References
7.1. Normative References
[IEEE754] IEEE Std 754-1985, IEEE Standard for Binary Floating-Point
Arithmetic.
[RFC3808] McDonald, I., "IANA Charset MIB", Informational, RFC 3808,
June 2004.
7.2. Informative References
[CHARSET] IANA Charset Registry (archived at):
http://www.iana.org/assignments/character-sets
Author's Address
Jim Eberle
1450 Lincoln Ave, Unit 9
Burlingame, CA 94010
EMail: jim.eberle@fastnlight.com
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Internet Draft Standard Data Types December 2006
Full Copyright Statement
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