Merge pull request #69 from donmendelson/issue40

Clarification on constant char encodings #40

Author: donmendelson

README.md

@@ -45,7 +45,7 @@ The [SBE Conformance project](https://github.com/FIXTradingCommunity/fix-sbe-con
 The XML namespace for SBE version 1.0 message schemas is [http://fixprotocol.io/2016/sbe](http://fixprotocol.io/2016/sbe).
 
 ## License
-FIX Simple Binary Encoding specifications are © Copyright 2014-2017 FIX Protocol Ltd.
+FIX Simple Binary Encoding specifications are © Copyright 2014-2018 FIX Protocol Ltd.
 
 <a rel="license" href="http://creativecommons.org/licenses/by-nd/4.0/"><img alt="Creative Commons License" style="border-width:0" src="https://i.creativecommons.org/l/by-nd/4.0/88x31.png" /></a><br /><span xmlns:dct="http://purl.org/dc/terms/" href="http://purl.org/dc/dcmitype/Text" property="dct:title" rel="dct:type">FIX Simple Binary Encoding</span> by <a xmlns:cc="http://creativecommons.org/ns#" href="http://www.fixtradingcommunity.org/" property="cc:attributionName" rel="cc:attributionURL">FIX Protocol Ltd.</a> is licensed under a <a rel="license" href="http://creativecommons.org/licenses/by-nd/4.0/">Creative Commons Attribution-NoDerivatives 4.0 International License</a>.<br />Based on a work at <a xmlns:dct="http://purl.org/dc/terms/" href="https://github.com/FIXTradingCommunity/fix-simple-binary-encoding" rel="dct:source">https://github.com/FIXTradingCommunity/fix-simple-binary-encoding</a>
 

v2-0-RC1/doc/01Introduction.md

@@ -9,7 +9,7 @@ intended to represent all FIX semantics.
 This encoding specification describes the wire protocol for messages.
 Thus, it provides a standard for interoperability between communicating
 parties. Users are free to implement the standard in a way that best
-suits their needs.
+suits their needs. Implementers may use the most appropriate techniques and idioms of programming languages to access data off the wire and manipulate it in applications.
 
 The encoding standard is complimentary to other FIX standards for
 session protocol and application level behavior.

v2-0-RC1/doc/02FieldEncoding.md

@@ -513,16 +513,23 @@ control character (code 0).
 
 #### Encoding of char type
 
-This is the standard encoding for char type.
+This is the standard encoding for char type. Note that the length attribute defaults to 1, producing a single character rather than a character array.
 
 ```xml
 <type name="charType" primitiveType="char"/>
 ```
 
+A field may be specified with a constant character value.
+```xml
+<field type="charType" name="OptAttribute" id="206" presence=constant>P</field>
+```
+
 Wire format of char encoding of "A" (ASCII value 65, hexadecimal 41)
 
 `41`
 
+
+
 ### Fixed-length character array
 
 Character arrays are allocated a fixed space in a message, supporting
@@ -532,7 +539,7 @@ attribute or a constant attribute.
 
 | FIX data type | Description     | Backing primitives                                                                                                          | Length (octets)               | Required schema attribute                                          |
 |---------------|-----------------|-----------------------------------------------------------------------------------------------------------------------------|-------------------------------|--------------------------------------------------------------------|
-| String        | character array | Array of char of specified length, delimited by NUL character if a string is shorter than the length specified for a field. | Specified by length attribute | length (except may be inferred from a constant value, if present). |
+| String        | character array | Array of char of specified length, delimited by NUL character if a string is shorter than the length specified for a field. | Specified by length attribute | length  |
 
 A length attribute set to zero indicates variable length. See [Variable-length string](#variable-length-string-encoding).
 
@@ -564,7 +571,7 @@ M S F T
 
 `4d5346540000`
 
-A character array constant specification
+A character array constant specification. As for a non-constant value, if the constant is shorter than the specified length, it should be padded with NUL characters to fill the fixed-length array.
 
 ```xml
 <type name="MarketID" primitiveType="char" length="4" description="MIC code"/>