Activities in Internet Explorer 8

IEBlog:

Under the hood, an Activity uses a simple XML format called OpenService. Just implement an XML file that describes how your service works with URL templates.

URL Template? Is that like a URI Template?

OpenService Format Specification for Activities

All variables are treated as required unless it [sic] the modifier "?"

Rats, those aren't URI Templates. But thanks for picking a different name.

Just for a little context, when discussing URI Templates the use of the trailing '?' was considered for marking a template variable optional, but in the end that was considered metadata and could appear in the surrounding document, just like it could appear the OpenService Format.

Question: URIs have a very limited character set. What happens if I have a URL Template that contains {selection} and I happen to select "☄"?