This part starts immediately after the section command and contains HTML tags intermingled with references to parts of the Algol 68 code (see section 3.3.2). The latter are delimited by the exclamation mark (also referred to as bang). The text will be passed unchanged to the output file by weav (apart from the snippets which will be formatted as Algol 68 source code) and completely ignored by tang. Here is an example from the uregex.w prelude:-
@ The library is initialised by !rx init! which takes as its only parameter a row of pairs of mode !STRUCT(INT ind,UCS val)!. A null row, specified as !()!, may also be given if the default meta-characters are acceptable. The routine yields !TRUE! if the parameters are satisfactory.
The HTML part can contain any HTML tags including mathematics. This example has been taken from the charbag.w prelude:-
@ (2) $b^b_i \leq c^e_s \Rightarrow$ the beginning of $b_i$ lies within $c_s$. There are two cases:- \begin{description} \item[(2.1)] $b^e_i \leq c^e_f$\newline The beginning ...