Note that the <SetVarBlock> preserves linefeeds. Using the block function as shown in the example above will put linefeeds into 'foo', so that you get LF(variable value)LF.

If your variable result is, say, the number 9, and you use the syntax in the example above, you will get:

LF
9
LF

In a certain situation, if you compare the generated value (using <mt:if> or <mt:unless>), the result will be incorrect.

To generate a variable value without linefeeds, use the following, all in one line:

<mt:setvarblock name="foo"><mt:foldercount></mt:setvarblock>

To strip linefeeds, use the strip_linefeeds modifier, like so:

<mt:setvarblock name="foo" strip_linefeeds="1">
    <mt:VariablesHereWhichCanNotBeSetWithMTVar>
</mt:setvarblock>

Thanks to Chris Hall for the heads up on this!