It's not the web pages, or whole templates I'm interested in, it's the components, ie. the bits included. For example:

thing.tt:

I am thing.
[download]

thang.tt:

I am thang.
[download]

fred.tt:

% INCLUDE thing.tt %

% INCLUDE thang.tt %
[download]

I ultimately want this from processing fred

<! -- begin fred.tt -->
<! -- begin thing.tt -->
I am thing.
<! -- end thing.tt -->
<! -- begin thang.tt -->
I am thang.
<! -- end thang.tt -->
<! -- end fred.tt -->
[download]

In this way, my designer can see which template components have been used to create a specific page

component is a special variable which is automatically set for each included component. The reason I said I had to pass it through is that it is set to the wrapper name if I don't pass it through from the component I want the information for.