The function char introduces a character in the produced document. The purpose of this function is to introduce escape characters or to introduce characters that cannot be typesetted in the document (for instance because the editors does not support them). The escapes characters are [, ] and ;.

(itemize (item [The character ,(code "#\\a"): ,(char #\a).])
          (item [The character ,(code "\"a\""): ,(char "a").])
          (item [The character ,(code "97"): ,(char 97).]))

... produces:

the function ! introduces raw strings in the target. That is, the strings introduced by ! are written as is, without any transformation from the engine.

The sequences $1, $2, ... in the format are replaced with the actual values of the arguments node.

[A simple ,(! "string"). A more annoying one ,(! "<strong>string</strong>"). 
A last one with arguments ,(! "<u>$1 $2</u>" (bold 1) (it 2)).]

... produces:

The function symbol introduces special symbols in the produced file. Note that the rendering of symbols is unportable. It depends of the capacity of the targeted format.

Here is the list of recognized symbols: