How to know whether I need @ in Razor Pages? : I want to know the rule when I have to use `@` in Razor pages.

For example,

    <div asp-validation-summary="ModelOnly">

    <input asp-for="Movie.ID" />

    <label asp-for="Movie.Title" ></label>

    <span asp-validation-for="Movie.Title" >

we don't need `@` but

    <a asp-page="Edit" asp-route-id="@Model.Movie.ID">Edit</a> 

we do need `@`.

What is the rule?