r3 provides and supports this XML Schema for compatibility with the ECA Framework (by translation between ECA-ML and r3). All the elements here included translate into elements of the r3 namespace and are limited versions of the ones supported by the ECA Framework . Currently, elements that do not belong to the eca or r3 namespaces are not supported outside of a response or of an eca : opaque (viz. any eca : Expression is ignored and may cause an error; unless it is an eca : opaque or an r3 : Expression ). Beware that none of the ECA Framework namespaces (viz. logic and eca) is slash (/) or hash (#) terminated. This element translates into an r3 : Load if it contains any eca : rule or any form of r3 : RulePackage . Otherwise it translates into an r3 : Install . This element translates into an r3 : Terminate . The <subject> refers to a previous register or asynch request (viz. for events). This element translates into an r3 : Evaluate . The <reply-to> is required to an asynch request (viz. for events). r3 : NormalizedExpression . This element is returned as a response to a request, viz.: register , deregister , request . It is a translation of the appropriate response to the associated request: r3 : Loaded or r3 : Installed , r3 : Terminated , r3 : EvaluateResponse . Errors processing a request may be signalled using an appropriate HTTP status (e.g. 500), in which case the body of the HTTP response is not expected to be a <response>. The <response> is usually returned synchrounously with the POST request, but it may also be used to asynchronously POST additional responses in case of a <request> that includes a <reply-to>. Refers to a register, a deregister or a request. Include only if subject refers to a request (even so, not required).