Thanks Jo.
I purposely called Mustache a template system to differentiate it from a framework, which in my mind is a totally different beast.
I agree that BSS should not be particularly interested in interfacing with other full frameworks like any of the PHP frameworks out there but that's not what Mustache is. In fact, you pretty much nailed its usefulness within BSS since it provides a way round the requests for including php code in BSS, which is why I think the ability use it in BSS would be useful. I'll give a couple of examples as you requested.
A simple Mustache template file might look something like this:
<html>
<head>
<title>Mustache Example</title>
</head>
<body>
<div class="form-group">
<label class="control-label">Name </label>
<input class="form-control" type="text" value="{{Name}}">
</div>
</body>
</html>
Note the string "{{Name}}". Prior to using Mustache, that would have been a php code snippet to load a value from a database, for example.
The php file associated with the template would look something like this.
<?php
//Get stuff from the database and put it into $dbarray
$msArray['Name']=$dbarray['Name'];
$template = $mustache->loadTemplate('msExample');
echo $template->render($msArray);
?>
No php code in the template file (which would be the BSS file), no html code in the php file, good code separation, easier to read and edit and the need for php code in BSS goes away.
In that example, I can do what I want in BSS since the placeholder {{Name}} is within a value attribute so I just need to type it into Bootstrap. However, here's another example which I don't believe can be done in BSS.
<table>
<thead>
<tr>
<th>Account</th>
<th>Name</th>
</tr>
</thead>
<tbody>
{{#Customers}}
<tr>
<td>{{Account}}</td>
<td>{{Name}}</th>
</tr>
</tbody>
</table>
{{/Customers}}
In this case {{#Customers}} and {{/Customers}} indicate the start and end of a section of html to be repeated for each key in the Customers array supplied to the Mustache render function, replacing the {{Account}} and {{Name}} placeholder with the values from the current Customers array key. Prior to Mustache, that whole section would have been inline php code to do the same thing or an include statement, neither of which are possible in BSS without resorting to custom code.
In this case, the placeholders are raw text strings in the html file and I don't believe BSS provides a way to do that. If it does, great, I welcome it and no need for any extra support from BSS.
Basically, with the addition of some sort of BSS raw text component with no validation or intelligent editing required, the need for php code in BSS goes away and it could be useful for other text strings, e.g. html comments. The BSS files become the Mustache templates, and the php script files can be created and maintained with your favorite editor.
I hope that explains the reason for my request and shows the difference between Mustache and a framework.