This tag "condenses" the contents so that if there is only white space between > and < characters, they will be removed.
This is especially useful when creating it is not wanted that HTML elements have white space between them and on the other hand it's inconvenient to write the mark up or B:tags without white spaces.
Examples
Condensing a navigation list
It is often useful to write <ul> tag without any white space characters between tags. By using <b:format.condense> this can be made conveniently without the need to write everything without white spaces.
Bildy itself does some cleaning of white space so that there wouldn't be overly excessive amount of white space that result for example from line feeds in B:tags. That is why the output without condensing isn't necessarily exactly what you'd expect it to be.
Without condensing:
<b:structure name="navi" parent="/">
<b:before><ul></b:before>
<li><a href="<b:navi.url/>"><b:navi.name/></a><b:navi.recursion parent="<b:navi.path/>"/></li>
<b:after></ul></b:after>
</b:structure>
With condensing:
<b:format.condense>
<b:structure name="navi2" parent="/">
<b:before><ul></b:before>
<li><a href="<b:navi2.url/>"><b:navi2.name/></a><b:navi.recursion parent="<b:navi2.path/>"/></li>
<b:after></ul></b:after>
</b:structure>
</b:format.condense>
HTML source output
Without condensing: <ul> <li><a href="/onboardR3/site/front-page">Front page</a></li> <li><a href="/onboardR3/site/products">Products</a><ul> <li><a href="/onboardR3/site/products/car">Car</a></li> <li><a href="/onboardR3/site/products/train">Train</a></li> <li><a href="/onboardR3/site/products/ship">Ship</a></li> </ul></li> </ul> With condensing: <ul><li><a href="/onboardR3/site/front-page">Front page</a></li><li><a href="/onboardR3/site/products">Products</a><ul><li><a href="/onboardR3/site/products/car">Car</a></li><li><a href="/onboardR3/site/products/train">Train</a></li><li><a href="/onboardR3/site/products/ship">Ship</a></li></ul></li></ul>
