Escape Slash before placeholder


I’m trying to escape a slash occuring before a placeholder, instead of escaping the acutal placeholder. In the manual I found the following remarks:

Unfortunately, this doesn’t specify the opposite, i.e. how to pass a placeholder with a slash in front. In my case I’m trying to pass the level of the LateX heading using custom placeholders in the prefix of a style:


Double slash doesn’t escape the slash but only a space seems to work, which however breaks the LaTeX command.