RFC 125 (rfc125) - Page 2 of 4

Response to RFC 86: Proposal for Network Standard Format for a Graphics Data Stream

The basic approach of transmitting an intermediate, device independent
language which is translated into specific device codes at the
receiving host is sound. It appears to be the only approach that will
allow thought to be centered on picture descriptions. Ames Research
Center has adopted this approach in tying its graphic facilities, of
various types, and on various computers together. At present, we are
in the design phase and expect our package to be running in about six
months. The main objections to the structure as it now exists, is that
it takes no cognizance of the many features available on graphics
devices. Since these features will always be changing with new
devices, a set of option or mode primitives should be defined which
are logically separate from the drawing primitives provided in RFC 86.
The mode primitives will act upon the drawing primitives to modify
their actions. The scope of a mode primitive extends until a new mode
primitive resets an option. The use of mode primitives will allow the
network standard stream interpreter to treat them as null operations
if the features are missing at a particular host, or to perform more
detailed interpretation of the following data stream to achieve
results. The drawing primitives may also then keep a standard format
which need not be changed to incorporate new features.

Overall modes which primitives could control would be intensity
levels, or color selections for objects, in addition blinking of
objects should be provided. For vectors, the additional facility for
drawing dashed lines is necessary.

Character strings require another set of specification. The convention
for the beam is usually that it is in the center of the rectangular
area defining a character's boundaries. The beam position is usually
undefined at the finish of drawing a character string. A strong
exception is taken to the exclusion of form control characters from
strings. If included in the character string, they could provide for
shifting from upper to lower case, subscripting, superscripting, and
underscoring, as well as tab and other "carriage" motion functions.
The appropriate characters could be extracted at interpretation time
to provide the necessary information to display more complex strings.
To allow the facility for generating ALGOL-like delimiters, such as
"then", a convention for canonical character string should be adopted.
I believe the Multics conventions described in reference 1 will
suffice.

Additional options for character strings should include a size
specification and an orientation selection. As many devices, have
hardware character generators that are fixed, some of these options
may not be desirable to implement as subroutines.

Another area that should be looked at further is the additional
symbols available which are not specified in ASCII. Some means of