How to write HTML5 data-atrribute in Razor MVC C#?

You can show data-attribute in Razor C#, by simply changing dashes(-) into underscrore, so your above code will be like this

@Html.DropDownListFor(m => m.Industry, OnePassV3.utility.OptionList.GetIndustryListSelectList()
                           , new { @class="cs-select cs-skin-slide cs-transparent", @data_init_plugin="cs-select" })

it will work in Razor view and will be rendered as data-init-plugin="cs-select".

You can try using "_" instead of "-" in MVC 4 or above, razor syntax

@Html.TextBoxFor(
    model => model.IteName, 
    new { data_url = Url.Action("ActionMethod", "Controller") }
)

If you are using older version of MVC

<%= Html.TextBoxFor(
    model => model.ItemName, 
    new Dictionary<string, object> { 
        { "data-url", Url.Action("ActionMethod", "Controller") } 
    }
) %>

That's it.