I'm having problems using DSL's in the guided editor specifically within the eclipse plugin. The simplest of rules using a DSL report a syntax error in eclipse. However, the same DSL rules (using the same DSL) are validated correctly in the normal drl editor in eclipse, and in the guided editor in the BRMS. Whatever condition I add to a rule in the eclipse guided editor, it always reports a validation error along the lines that the first word in the when part of my DSL rule is an unexpected token. It's as if the editor is trying to validate the DSL sentence itself, rather than the translation of the DSL sentence. Here's the simplest example I could think off to reproduce the issue: 1. I have a single DSL sentence in my .dsl file as follows: [condition][]string=String() (I've used String as it avoids having to import a model to recreate this issue) 2. In eclipse I create a new file called rule.package containing: package com.example import java.lang.String 3. In the guided editor in eclipse I create a new rule by clicking on the add condition on the When part of the rule and choosing the single DSL sentence in the drop-down list displayed by the add condition dialog to get the rule: When string Then 4. I get an error in the list of error that says that string is an unexpected token. 5. I noticed that in the "Generated DRL (read only)" tab under the guided editor, it also displays the rule in DSL format, and not translated into the expressions on the right-hand-side of the DSL definition. This made me wonder if the eclipse guided editor is trying to validate the DSL rule without applying the DSL translation. So I deliberately changed my DSL so that the left-hand-side just happened to be a valid technical rule condition: [condition][]String()=String() I also changed the rule in the guided editor to When String() Then This was validated without any issues, but in theory is exactly the same rule as in point 3 as, apart from keywords, it shouldn't matter what is on the left-hand -side of the DSL definition. As I said at the beginning, the dsl and rule in point 1 and 3 work fine with the normal drl editor in the eclipse plugin, and within the guided editor in the BRMS. I also tried adding the expander definition to point to my DSL file in the rule.package file, but that made no difference either. Regards Shahad