This is the subscript for the START character in the special control
character array. termios
.c_cc[VSTART] holds the
The START character is used to support the
input modes. If
IXON is set, receiving a START character resumes
suspended output; the START character itself is discarded. If
IXANY is set, receiving any character at all resumes suspended
output; the resuming character is not discarded unless it is the START
IXOFF is set, the system may also transmit START
characters to the terminal.
The usual value for the START character is C-q. You may not be
able to change this value—the hardware may insist on using C-q
regardless of what you specify.