config: Do not allow runtimes to ignore properties defined by the spec

wking · wking · commit 19ed44c560e6 · 2017-02-07T14:56:07.000-08:00
Otherwise a runtime could silently ignore a property it didn't want to implement, which would be confusing for runtime callers [1]. This closes a potential loophole in the restriction from 766abd6 (runtime.md: Require 'create' to fail if config.json asks for the impossible, 2016-09-08, #559). [1]: #472 (comment) Signed-off-by: W. Trevor King <wking@tremily.us>
diff --git a/config.md b/config.md
@@ -415,6 +415,7 @@ Values MAY be an empty string.
 ## Extensibility
 Implementations that are reading/processing this configuration file MUST NOT generate an error if they encounter an unknown property.
 Instead they MUST ignore unknown properties.
+Properties defined for the [target platform](#platform) by the [declared version](#specification-version) of this specification MUST NOT be ignored.
 
 ## Configuration Schema Example
 
