What is the maximum nesting of opml?

Question

RSS

The format specification says:
An is an XML element containing at least one required attribute, text, and zero or more additional attributes. An may contain zero or more sub-elements. No attribute may be repeated within the same element.
I'm interested in what is the maximum nesting depth supported by this format.
For example, when exporting records in OPML format from Google Reader, this depth is 2.

Answer 1

Obviously, the nesting format is not limited. But some readers can limit.