Currently TemplateData support a Default Value in its specification, but it would be convenient to amend this with a set of suggested values. These values could be served to the user trough a combobox (Input + Dropdown) where one could either type a value, or select one from the dropdown list.
Rationale for this:
Many templates a small set of accepted values for a single parameter. For example, [[Template:Coord]] contains the "Display" parameter that accepts the values "Inline", "Title" and "Inline+Title". Having these in a dropdown would be more convenient then having to type them (Which would require browsing to the documentation as well). The same applies to the "Type" parameter in that template, which has multiple values as well.
I suppose this could use three parameters:
- ParameterName (The name of the parameter)
- Alias (The non cryptic name of the parameter, displayed in the dropdown)
- Description (A help text that displays what the parameter value does / is intended for)