Another special case of a word is a wildcard.
{ $*$ $\vert$ $\%$ $\vert$ $\char93 $ $\vert$ $+$ $\vert$ $<$string$>$ }
$*$ matches any string.
$\%$ matches a single character.
$\char93 $ matches any number.
$+$ matches any digit.
It is used to match a construct against sets of other words. The possibility of a wildcard specification is also indicated by enclosing syntactic constructs in $<$* *$>$ angle brackets.


Xplor-NIH 2023-11-10