**Feature summary** (what you would like to be able to do and where):
It is possible to specify suggested values in the TemplateData. Their support is implemented in the VisualEditor. Their use simplifies template customization and helps the user to understand it.
**Use case(s)** (list the steps that you performed to discover that problem, and describe the actual underlying problem which you want to solve. Do not describe only a solution):
* Try to insert any template with suggested values, for example, https://www.mediawiki.org/wiki/Template:Graph:PageViews - Interpolate parameter
* Add this parameter and tru to understand what it want :)
**Benefits** (why should this be implemented?):
Users will make fewer mistakes, and there will be no need to duplicate the proposed values in the parameter description.