Telnet Data Entry Terminal option(3)

　　The three bits of the Intensity field will contain a positive binary　integer indicating the number of levels of intensity that the sender　requests or provides for displaying the data. The value of the 3 bit　field should be interpreted in the following way:

　　1 one visible intensity

　　2 two intensities; normal and bright

　　3 three intensities; off, normal, and bright　>3 >3 intensities; off, and the remaining levels　proportioned from dimmest to brightest intensity.

　　For the all of the above commands, if the appropriate bit in　is not set, then the sender does not request or　provide that facility.

　　Editing Functions

　　IAC SB DET MOVE CURSOR IAC SE subcommand code: 5

　　where is an 8-bit byte containing a positive binary integer　representing the character position of the cursor, is an 8-bit　byte containing a positive binary integer representing the line　position of the cursor.

　　This subcommand moves the cursor to the absolute screen address　(x,y) with the following boundary conditions:

　　if x>M-1, set x=M-1 and send an ERROR subcommand

　　if y>N-1, set y=N-1 and send an ERROR subcommand

　　This describes a finite plane topology on the screen.

　　IAC SB DET SKIP TO LINE IAC SE subcommand code: 6　where is a positive 8-bit binary number.

　　This subcommand moves the cursor to the absolute screen line y. x　remains constant. For values of y>N-1

　　y = y mod N.

　　IAC SB DET SKIP TO CHAR IAC SE subcommand code: 7　where is a positive 8-bit binary number.

　　This subcommand moves the cursor to the absolute character position　x. y remains constant, unless x>M-1 in which case:

　　x' = (x mod M)

　　y' = (y+(x DIV N))

　　where x' and y' are the new values of the cursor.

　　These last two subcommands define a toroidal topology on the screen.

　　IAC SB DET UP IAC SE subcommand code: 8

　　IAC SB DET DOWN IAC SE subcommand code: 9

　　IAC SB DET LEFT IAC SE subcommand code: 10

　　IAC SB DET RIGHT IAC SE subcommand code: 11

　　These subcommands are provided as a convenience for some terminals.

　　The commands UP, DOWN, LEFT, and RIGHT are defined as

　　UP: (x,y)=(x, y-1 mod N)

　　DOWN: (x,y)=(x, y+1 mod N)

　　LEFT: (x,y)=(x-1, y); if x=0 then x-1 = 0

　　RIGHT: (x,y)=(x+1 mod M, y) and y = y+1 if x+1>M-1

　　Note: DOWN, LEFT, and RIGHT cannot always be replaced by the ASCII

　　codes for linefeed, backspace, and space respectively. The latter　are format effectors while the former are cursor controls.

　　IAC SB DET HOME IAC SE subcommand code: 12

　　This subcommand positions the cursor to (0,0). This is equivalent to　a MOVE CURSOR 0,0 or the sequence SKIP TO LINE 0, SKIP TO CHAR 0.

　　This subcommand is provided for convenience, since most terminals　have it as a separate control.

　　IAC SB DET LINE INSERT IAC SE subcommand code: 13

　　This subcommand inserts a line of spaces between lines y (the　current line, determined by the position of the cursor) and line　y-1. Lines y through N-2 move down one line, i.e. line y becomes　line y+1; y+1 becomes y+2, ...; N-2 becomes N-1. Line N-1 is lost　off the bottom of the screen. The position of the cursor remains　unchanged.

　　IAC SB DET LINE DELETE IAC SE subcommand code: 14

　　This subcommand deletes line y where y is the current line position　of the cursor. Lines y+1 through N-1 move up one line, i.e. line y+1　becomes line y; y+2 becomes y+1; ...; N-1 becomes N-2. The N-1st　line position is set to all spaces. The cursor position remains　unchanged.

　　IAC SB DET CHAR INSERT IAC SE subcommand code: 15

　　This subcommand inserts the next character in the data stream　between the xth and x-1st characters, where x is the current　character position of the cursor. The xth through M-2nd characters　on the line are shifted one character positon to the right. The new　character is inserted at the vacated xth position. The M-1st　character is lost. The position of the cursor remains unchanged.

　　IAC SB DET CHAR DELETE IAC SE subcommand code: 16　This subcommand deletes the character on the screen at the x-th　position. The x-th character is removed and the characters x+1　through M-1 are shifted one character position to the left to become　the x-th through M-2nd characters. The M-1st character position is　left empty. (For most terminals it will be set to a NUL or space.)

　　The cursor position remains unchanged.