Passthrough Blocks

The pass style and delimited passthrough block exclude the block’s content from all substitutions unless the subs attribute is set.

Pass style syntax

The pass style can also be set on a paragraph or an open block.

[pass]
<u>underline me</u> is underlined.

Delimited passthrough block syntax

A passthrough block is delimited by four plus signs (++++).

++++
<video poster="images/movie-reel.png">
  <source src="videos/writing-zen.webm" type="video/webm">
</video>
++++

(Keep in mind that AsciiDoc has a video macro, so this example is merely for demonstration. However, a passthrough could come in handy if you need to output more sophisticated markup than what the built-in HTML converter produces).

Control substitutions on a passthrough block

You can use the subs attribute to specify a comma-separated list of substitutions. These substitutions will be applied to the content prior to it being reintroduced to the output document.

[subs=attributes]
++++
{name}
image:tiger.png[]
++++

The content of the pass block does not get wrapped in a paragraph. Therefore, you can use the pass style in combination with the normal substitution category to output content without generating a paragraph.

[subs=normal]
++++
Normal content which is not enclosed in a paragraph.
++++

Using passthroughs to pass content (without substitutions) can couple your content to a specific output format, such as HTML. In these cases, you should use conditional preprocessor directives to route passthrough content for different output formats based on the current backend.