src/dtos.md

 ## DTO
 
+All DTOs use [`class-validator`](https://github.com/typestack/class-validator) for validation. A [`ValidationPipe`](./shared#validationpipets) decorator is needed in the controllers to trigger the validation.
+
 `ValidateNested()` and `Type(() => DTO)` is needed for ValidationPipe to validate nested DTOs.
 
 ? in the key's name means, that the key-value pair is optional.
@@ -249,3 +251,18 @@ export class GeoDTO {
   time: number;
 }
 ```
+
+### NotificationDTO
+
+```typescript
+export class NotificationdDTO {
+  // alert is for serious messages, note is for smaller updates on a situation
+  @IsIn(["alert", "note"])
+  type: string;
+  @IsString()
+  @Length(0, 63)
+  message: string;
+  @IsUUID("4")
+  game: string;
+}
+```