Clarify meaning of IXANY.

Clarify relationship of MIN with VMIN and TIME with VTIME.
Noted that CIBAUD, OFDEL, and DELECHO are not implemented on Linux.
Added explanatory paragraph for phrases "not in POSIX" and
"XSI".

man3/termios.3

@@ -93,6 +93,11 @@ only exposed if a specific feature test macro (see
 .BR ftm (7))
 is defined, as noted in brackets ("[]").
 .PP
+In the descriptions below, "not in POSIX" means that the
+value is not specified in POSIX.1-2001, 
+and "XSI" means that the value is specified in POSIX.1-2001 
+as part of the XSI extension.
+.PP
 \fIc_iflag\fP flag constants:
 .TP
 .B IGNBRK
@@ -139,7 +144,8 @@ Translate carriage return to newline on input (unless \fBIGNCR\fP is set).
 Enable XON/XOFF flow control on output.
 .TP
 .B IXANY
-(not in POSIX.1; XSI) Enable any character to restart output.
+(XSI) Typing any character will restart stopped output.  
+(The default is to allow just the START character to restart output.)
 .TP
 .B IXOFF
 Enable XON/XOFF flow control on input.
@@ -177,6 +183,7 @@ Send fill characters for a delay, rather than using a timed delay.
 .B OFDEL
 (not in POSIX) Fill character is ASCII DEL (0177).
 If unset, fill character is ASCII NUL ('\\0').
+(Not implemented on Linux.)
 .TP
 .B NLDLY
 Newline delay mask.  Values are \fBNL0\fP and \fBNL1\fP.
@@ -215,9 +222,10 @@ Form feed delay mask.  Values are \fBFF0\fP or \fBFF1\fP.
 .B CBAUDEX
 (not in POSIX) Extra baud speed mask (1 bit), included in CBAUD.
 [requires _BSD_SOURCE or _SVID_SOURCE]
-.LP
-(POSIX says that the baud speed is stored in the termios structure
-without specifying where precisely, and provides
+.sp
+(POSIX says that the baud speed is stored in the 
+.I termios 
+structure without specifying where precisely, and provides
 .BR cfgetispeed ()
 and
 .BR cfsetispeed ()
@@ -252,12 +260,13 @@ Ignore modem control lines.
 .TP
 .B LOBLK
 (not in POSIX) Block output from a noncurrent shell layer.
-For use by \fBshl\fP (sjhell layers).  (Not implemented on Linux.)
+For use by \fBshl\fP (shell layers).  (Not implemented on Linux.)
 .TP
 .B CIBAUD
 (not in POSIX) Mask for input speeds. The values for the CIBAUD bits are
 the same as the values for the CBAUD bits, shifted left IBSHIFT bits. 
 [requires _BSD_SOURCE or _SVID_SOURCE]
+(Not implemented on Linux.)
 .TP
 .B CRTSCTS
 (not in POSIX) Enable RTS/CTS (hardware) flow control.
@@ -315,6 +324,7 @@ each character on the line, as specified by \fBECHOE\fP and \fBECHOPRT\fP.
 .TP
 .B DEFECHO
 (not in POSIX) Echo only when a process is reading.
+(Not implemented on Linux.)
 .TP
 .B FLUSHO
 (not in POSIX; not supported under Linux)
@@ -445,9 +455,11 @@ status request: 024, DC4, Ctrl-T).
 .LP
 These symbolic subscript values are all different, except that
 VTIME, VMIN may have the same value as VEOL, VEOF, respectively.
-(In non-canonical mode the special character meaning is replaced
-by the timeout meaning. MIN represents the minimum number of characters
-that should be received to satisfy the read. TIME is a decisecond-valued
+In non-canonical mode the special character meaning is replaced
+by the timeout meaning. 
+MIN (indexed using VMIN) represents the minimum number of characters
+that should be received to satisfy the read. 
+TIME (indexed using VTIME) is a decisecond-valued
 timer. When both are set, a read will wait until at least one character
 has been received, and then return as soon as either MIN characters
 have been received or time TIME has passed since the last character
@@ -455,7 +467,7 @@ was received. If only MIN is set, the read will not return before
 MIN characters have been received. If only TIME is set, the read will
 return as soon as either at least one character has been received,
 or the timer times out. If neither is set, the read will return
-immediately, only giving the currently already available characters.)
+immediately, only giving the currently already available characters.
 .PP
 .BR tcgetattr ()
 gets the parameters associated with the object referred by \fIfd\fP and