If the very first or very last character of an argument is a newline, then that character is ignored if it would be part of a regular plaintext node.
generates something like:
\C[[ a b ]]
This is extremely convenient to improve the readability of code blocks and similar constructs.
<pre><code> a b </code></pre>
The newline is however considered if it would be part of some insane macro shortcut. For example, we can start an insane list inside a quotations as in:
\Q[ * a * b ]
which renders as:
where the insane list requires a leading newline
\n*to work. That newline is not ignored, even though it comes immediately after the