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Graphics
Table D-2. Summary of Graphics Sequence Types
ESCAPE SEQUENCE
DESCRIPTION
Ec *
d
Display Control
Ec *
1
Labeling
Ec *
m
Drawing Mode
Ec *
p
Vector Plotting
Ec *
5
Graphics Status
Ec *
t
Compatibility Mode
Ec *
'II
Graphics Initialization
Control Codes
Control codes are generally ignored, with the exception of the ESCAPE character (Ec). Ifan Ec
character is detected and the previous graphics control sequence has not been properly
terminated with a CCZ"or some other valid upper case character, the Ec will cause the execution of
the previous sequence to be terminated. The new escape sequence will then be executed.
Commands
Graphics commands come from columns 4-7 of the ASCII table, the upper and lower case letter
(A-Z and
A).
Both upper and lower case commands execute the same function. Upper case letters
terminate the sequence and cause it to be executed. You can use more than one command in a
sequence.
Graphics sequences can be any length. (The terminal ignores CR and LF characters in the
middle of graphics sequences.) For example, to plot a figure containing 100 points the escape
sequence could appear as follows:
Ec
*
p
a
(x1,y1> . . . (x100,y100>Z
This could cause problems if an error occurs and the system tries to report it in the middle of a
long sequence. Since most systems use upper case characters for messages, the first character
of the message would end any graphics sequence that might be in progress. Letters that have
not been assigned a function for a particular graphics sequence are treated as NOP's and if they
are lower case, are ignored. If upper case, they will end the sequence. The letter z has been
defined as a NOP in all sequences so that a capital Z can always be used to end a graphics
escape sequence.
D-4
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