R2RML - escaping "{" and "}"

In the R2RML specification I don't see a description of how to escape the
characters "{" and "}" in template strings. For example if I need to produce
a string like "{joe 25}" from a name and age column then I would want to
have a template something like: "{{name} {age}}", but I expect the outer
braces would need to be escaped somehow, perhaps as: "\{{name} {age}\}". Is
this something that the specification will address?

Thank you.
-David McNeil