Syntax for using placeholders with ical feed

Hello–

Is it possible to use placeholders in the URLs for ical feeds? If so what is the syntax?

I have users who would like to subscribe in their Google Calendars to events with a specific category in a site where events are handled using Events Manager.

There is a placeholder: #_CATEGORYICALURL that can be used to display “the URL of the event ical feed (ics file format) which shows all events with this category.” Can I use this, with a category ID or slug, to create a modification to <mysiteURL>/events.ics?

Thanks–