This is the subscript for the WERASE character in the special control
character array. termios
.c_cc[VWERASE] holds the character
The WERASE character is recognized only in canonical mode. It erases an
entire word of prior input, and any whitespace after it; whitespace
characters before the word are not erased.
The definition of a “word” depends on the setting of the
ALTWERASE mode; see Local Modes.
ALTWERASE mode is not set, a word is defined as a sequence
of any characters except space or tab.
ALTWERASE mode is set, a word is defined as a sequence of
characters containing only letters, numbers, and underscores, optionally
followed by one character that is not a letter, number, or underscore.
The WERASE character is usually C-w.
This is a BSD extension.