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NAPLPS is the North American Presentation Level Protocol Syntax, an ANSI
standard defining a scheme for encoding graphical data in textual form.
It's usually thought of in terms of videotex services but has a lot
of other applications where compact coding of colour, text attributes,
geometric shapes, foreign languages and so on are needed.

Since the original discussion in this newsgroup centered around storing
video attributes in a text file, here are some appropriate examples.
In these examples (as in the standard), characters are referred to
by their column/row position in a table - the character 4/1 corresponds
to hexadecimal 41, or 'A'.

NAPLPS revolves around different character sets. Two useful ones are the
G2 set of supplementary characters (accents, fractions, currency symbols
and so on) and the C1 set of miscellaneous commands that don't fit
nicely into one of the other sets.

If we wanted to underline a word in a line, we could do it with this
sequence of characters -

"this word is"
ESC 5/9    /* the C1 command for 'Underline Start' */
"underlined"
ESC 5/10   /* C1 for "underline stop" */

You can get reverse video in a similar way, using ESC 4/8 and ESC 4/9;
you can get a word to ESC 4/14 blink ESC 5/15 or do a whole bunch
of neat tricks with colour.

In addition using the Supplementary Character Set, you have quick access
to properly accented characters or a whole variety of useful symbols.  

For more information you can see the ANSI standard itself or check
out a series in BYTE starting in February 1983.

(I hope I didn't get any of the control sequences wrong.  Those of
you in the know might observe that the logical pel has to be set to
a non-zero value in order that underlining will work.)

Steve Hayman
watmath!watcgl!sahayman