diff --git a/src/vs/editor/common/modes/languageFeatureRegistry.ts b/src/vs/editor/common/modes/languageFeatureRegistry.ts
index 2ffe037a5ba..c5e4e7010d8 100644
--- a/src/vs/editor/common/modes/languageFeatureRegistry.ts
+++ b/src/vs/editor/common/modes/languageFeatureRegistry.ts
@@ -18,6 +18,16 @@ interface Entry<T> {
 	_time: number;
 }
 
+function isExclusive(selector: LanguageSelector): boolean {
+	if (typeof selector === 'string') {
+		return false;
+	} else if (Array.isArray(selector)) {
+		return selector.every(isExclusive);
+	} else {
+		return selector.exclusive;
+	}
+}
+
 export default class LanguageFeatureRegistry<T> {
 
 	private _clock: number = 0;
@@ -142,6 +152,16 @@ export default class LanguageFeatureRegistry<T> {
 
 		for (let entry of this._entries) {
 			entry._score = score(entry.selector, model.uri, model.getLanguageIdentifier().language, shouldSynchronizeModel(model));
+
+			if (isExclusive(entry.selector) && entry._score > 0) {
+				// support for one exclusive selector that overwrites
+				// any other selector
+				for (let entry of this._entries) {
+					entry._score = 0;
+				}
+				entry._score = 1000;
+				break;
+			}
 		}
 
 		// needs sorting
diff --git a/src/vs/editor/common/modes/languageSelector.ts b/src/vs/editor/common/modes/languageSelector.ts
index a5bac2ab4fb..513ca2cc2d6 100644
--- a/src/vs/editor/common/modes/languageSelector.ts
+++ b/src/vs/editor/common/modes/languageSelector.ts
@@ -16,6 +16,7 @@ export interface LanguageFilter {
 	 * This provider is implemented in the UI thread.
 	 */
 	hasAccessToAllModels?: boolean;
+	exclusive?: boolean;
 }
 
 export type LanguageSelector = string | LanguageFilter | (string | LanguageFilter)[];
@@ -43,8 +44,8 @@ export function score(selector: LanguageSelector, candidateUri: URI, candidateLa
 		}
 
 		// short-hand notion, desugars to
-		// 'fooLang' -> [{ language: 'fooLang', scheme: 'file' }, { language: 'fooLang', scheme: 'untitled' }]
-		// '*' -> { language: '*', scheme: '*' }
+		// 'fooLang' -> { language: 'fooLang'}
+		// '*' -> { language: '*' }
 		if (selector === '*') {
 			return 5;
 		} else if (selector === candidateLanguage) {
diff --git a/src/vs/vscode.proposed.d.ts b/src/vs/vscode.proposed.d.ts
index 17f98c7bf01..10bc6631678 100644
--- a/src/vs/vscode.proposed.d.ts
+++ b/src/vs/vscode.proposed.d.ts
@@ -488,4 +488,12 @@ declare module 'vscode' {
 	}
 
 	//#endregion
+
+	//#region Joh -> exclusive document filters
+
+	export interface DocumentFilter {
+		exclusive?: boolean;
+	}
+
+	//#endregion
 }
diff --git a/src/vs/workbench/api/node/extHost.api.impl.ts b/src/vs/workbench/api/node/extHost.api.impl.ts
index d35d3e69609..0c2c16c0ea9 100644
--- a/src/vs/workbench/api/node/extHost.api.impl.ts
+++ b/src/vs/workbench/api/node/extHost.api.impl.ts
@@ -147,18 +147,23 @@ export function createApiFactory(
 		// we cannot say if the extension is doing it right or wrong...
 		let checkSelector = (function () {
 			let done = initData.environment.extensionDevelopmentPath !== extension.extensionFolderPath;
-			function inform(selector: vscode.DocumentSelector) {
-				console.info(`Extension '${extension.id}' uses a document selector without scheme. Learn more about this: https://go.microsoft.com/fwlink/?linkid=872305`);
-				done = true;
+			function informOnce(selector: vscode.DocumentSelector) {
+				if (!done) {
+					console.info(`Extension '${extension.id}' uses a document selector without scheme. Learn more about this: https://go.microsoft.com/fwlink/?linkid=872305`);
+					done = true;
+				}
 			}
 			return function perform(selector: vscode.DocumentSelector): vscode.DocumentSelector {
-				if (!done) {
-					if (Array.isArray(selector)) {
-						selector.forEach(perform);
-					} else if (typeof selector === 'string') {
-						inform(selector);
-					} else if (typeof selector.scheme === 'undefined') {
-						inform(selector);
+				if (Array.isArray(selector)) {
+					selector.forEach(perform);
+				} else if (typeof selector === 'string') {
+					informOnce(selector);
+				} else {
+					if (typeof selector.scheme === 'undefined') {
+						informOnce(selector);
+					}
+					if (!extension.enableProposedApi && typeof selector.exclusive === 'boolean') {
+						throwProposedApiError(extension);
 					}
 				}
 				return selector;
diff --git a/src/vs/workbench/api/node/extHost.protocol.ts b/src/vs/workbench/api/node/extHost.protocol.ts
index 19423ae8218..ed29c4320ed 100644
--- a/src/vs/workbench/api/node/extHost.protocol.ts
+++ b/src/vs/workbench/api/node/extHost.protocol.ts
@@ -258,6 +258,7 @@ export interface ISerializedDocumentFilter {
 	language?: string;
 	scheme?: string;
 	pattern?: vscode.GlobPattern;
+	exclusive?: boolean;
 }
 
 export interface MainThreadLanguageFeaturesShape extends IDisposable {
diff --git a/src/vs/workbench/api/node/extHostLanguageFeatures.ts b/src/vs/workbench/api/node/extHostLanguageFeatures.ts
index a5032c4686c..4c22a34d548 100644
--- a/src/vs/workbench/api/node/extHostLanguageFeatures.ts
+++ b/src/vs/workbench/api/node/extHostLanguageFeatures.ts
@@ -887,7 +887,8 @@ export class ExtHostLanguageFeatures implements ExtHostLanguageFeaturesShape {
 				$serialized: true,
 				language: selector.language,
 				scheme: this._transformScheme(selector.scheme),
-				pattern: selector.pattern
+				pattern: selector.pattern,
+				exclusive: selector.exclusive
 			};
 		}
 
diff --git a/src/vs/workbench/api/node/extHostTypeConverters.ts b/src/vs/workbench/api/node/extHostTypeConverters.ts
index 149733b823a..c8aec09c9de 100644
--- a/src/vs/workbench/api/node/extHostTypeConverters.ts
+++ b/src/vs/workbench/api/node/extHostTypeConverters.ts
@@ -696,7 +696,8 @@ function doToLanguageSelector(selector: string | vscode.DocumentFilter): string
 		return {
 			language: selector.language,
 			scheme: selector.scheme,
-			pattern: toGlobPattern(selector.pattern)
+			pattern: toGlobPattern(selector.pattern),
+			exclusive: selector.exclusive
 		};
 	}