grammar org.xtext.example.mydsl.MyDsl with org.eclipse.xtext.common.Terminals
    // in my file the next two lines do not contain spaces inbetween the links 
    // I just had to do this because of the forum rules 
    generate myDsl "http:// www. xtext.org/example/mydsl/MyDsl"
    import "http:// www. eclipse.org/emf/2002/Ecore" as ecore 
    
    ComplexGrammar:
        'Define Complex Grammar'
        (
            'Define Some Value {' someValues+=SomeValue+ '}'
            & 'Define Parts {' requiredParts+=RequiredPart+ '}'
            & 'Define FeatureX {' xfeatures+=FeatureX+ '}'
            & 'Define FeatureY {' yfeatures+=FeatureY+ '}'
        )
        'End'
    ;
    
    RequiredPart:
        'Part' name=ID ';'
    ;
    
    FeatureX:
        // I need this part of the grammar in a single editor.
        // It should support the Xtext validation to show errors.
        // The editor should only use FeatureX instead of the whole grammar.
        // But it also needs RequiredPart which is necessary for the complex grammar, too.
        'Here it requires' requiredPart = [RequiredPart]
    ;
    
    FeatureY:
        // The same like FeatureX, but for FeatureY
        'Requires' requires = [RequiredPart] 'for FeatureY, too!'
    ;
    
    SomeValue:
        // This part is not required by FeatureX or FeatureY
        // But it is required for the ComplexGrammar
        'Unimportant' name=ID 'Value' value=Double ';'
    ;
    
    Double returns ecore::EDouble:
        '-'? INT? '.' INT
    ;

    Define Complex Grammar
        Define Parts {
            Part GlobalPartA ;
            Part GlobalPartB ;
        }
        
        Define FeatureX {
            Here it requires GlobalPartA  
        }
        
        Define FeatureY {
            Requires GlobalPartA for FeatureY, too!
            
            Requires GlobalPartB for FeatureY, too!
        }
        
        Define Some Value {
            Unimportant ObjName Value 1.0 ;
        }
        
    End

    Define FeatureY {
        Requires GlobalPartA for FeatureY, too!
        
        Requires GlobalPartB for FeatureY, too!
    }