The use of the %% nop %% WCTL directive is sometimes obscure.

Basically %% nop %% does nothing! "nop" is short for "no operation".

The reason it exists is that WCTL suppresses the CRLF immediately
following any %%...%% directive. So

<a href...>%%nop%%
< ...>

is actually output as

<a href...><img ...>

(because leading tabs are suppressed, and the %%nop%% suppresses the crlf).

So basically it allows you to write more readable HTML, without
having to run long strings together (ala our toolbar layout, where
extra white space causes spaces between the buttons).