anchor.diff:  schemaExtension: 'extend' schemaDefinition ;
   typeExtension: 'extend' typeDefinition;
   
  -// original code: execution definitions 
  +// original code: execution definitions
   // GraphQL Draft Specification - July 2015
   execDefinition: operationDefinition | fragmentDefinition;
   
   operationDefinition:
   	selectionSet
  -	| operationType NAME variableDefinitions? directives? selectionSet;
  -
  -selectionSet: '{' selection ( ','? selection)* '}';
  +	| operationType NAME? variableDefinitions? directives? selectionSet;
  +
  +selectionSet: '{' selection+ '}';
   
   operationType: 'query' | 'mutation' | 'subscription';
   
   selection: field | fragmentSpread | inlineFragment;
   
  -field: fieldName arguments? directives? selectionSet?;
  -
  -fieldName: alias | NAME;
  -
  -alias: NAME ':' NAME;
  -
  -arguments: '(' argument ( ',' argument)* ')';
  -
  -argument: NAME ':' valueOrVariable;
  +field: alias? fieldName arguments? directives? selectionSet?;
  +
  +fieldName: NAME;
  +
  +alias: NAME ':';
  +
  +arguments: '(' argument+ ')';
  +
  +argument: NAME ':' value;
   
   fragmentSpread: '...' fragmentName directives?;
   
  
positive.code: directiveLocations: directiveLocation ('|' directiveLocations)*;
  directiveLocation: executableDirectiveLocation | typeSystemDirectiveLocation;
  
  executableDirectiveLocation: 
  'QUERY' |
  'MUTATION' |
  'SUBSCRIPTION' |
  
negative.code: directives:  directive+;
  
  directive:
  	'@' NAME arguments?;
  
  typeCondition: typeName;
  
  variableDefinitions: '(' variableDefinition+ ')';
  
  variableDefinition: variable ':' type_ defaultValue?;
  
  