The tag B, defines a block and we'll just call it the block tag from now on. A block won't be shown in the generated HTML, it is completely stripped away. Its contents can however be assigned to a value tag. This is done from Java code with a call to setBlock. In other words, a block can be thought of as a building block which can later be used to construct the page. In the guess template there are several blocks defined, but only one of them is used at a time.

if (game.getAnswer() < guess)
{
  mTemplate.setBlock("indication", "lower");
}
else if (game.getAnswer() > guess)
{
  mTemplate.setBlock("indication", "higher");
}

This piece of code from the Java implementation of the guess element shows how the lower and higher blocks are used together with the value placeholder indication. Remember, the contents of a block only appears if it has been assigned to a value.