<Li> variable ~ / regex / returns true if the variable is matched . </Li> <Li> variable! ~ / regex / returns false if the variable is matched . </Li> <P> A variant of this, with the plain tilde replaced with = ~, was adopted in Perl, and this semi-standardization has led to the use of these operators in other programming languages, such as Ruby or the SQL variant of the database PostgreSQL . </P> <P> In APL and MATLAB, tilde represents the monadic logical function NOT . </P>

What is the name of the part of the wave that is labeled with the question mark