[Konsole-devel] [Bug 107487] Please add the xterm-256 colour support.

[Lars Doelle]

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------- Additional Comments From lars.doelle on-line de  2006-06-07 02:03 -------
Hmm, a quick follow up...

On Tuesday 06 June 2006 23:20, lars.doelle on-line de wrote:

> The code really spells
> : 48 - set default background color
> :   5 - set blink
> : <PS> - for <Color> in most cases an unknown name.


Here i am wrong - 48 is not defined, at least not for VT100 and its successors.
Neverthenless it does not invalidate my argumentation. See e.g.

http://vt100.net/docs/vt100-ug/chapter3.html#S3.3.2

which is very clear about the association. Thus 48 would be ignored, 5 would set
blink and any defined value for PS would legal be interpreted as such by virtually
any terminal which emulates a VT100 based set of ESC codes. The extension is
incompatible.

But - ECMA-48:

http://www.ecma-international.org/publications/files/ecma-st/ECMA-048.pdf

See §8.3.117 (SGR), page 62
---
38 (reserved for future standardization; intended for setting character foreground colour as specified in
   ISO 8613-6 [CCITT Recommendation T.416])
48 (reserved for future standardization; intended for setting character background colour as specified in
   ISO 8613-6 [CCITT Recommendation T.416])
---

Hmm, ISO/IEC 8613-6:1994 - this means $$$

http://www.iso.org/iso/en/CatalogueDetailPage.CatalogueDetail?CSNUMBER=22943
Add to shopping basket  Size     Price
  ISO/IEC 8613-6:1994 PDF version (en)  15052 KB     CHF 164,00

The codes may or may not be defined as used in xterm, moving the whole thing in safer waters,
especially with respect to codes 38,48.

Anyway still issues. How is this supposed to work? Keep in mind that the code is associative. Citing
ECMA-48:

---
5.4.3 Types of parameters
      In a control sequence with parameters, each parameter sub-string corresponds to one parameter and
      represents the value of that parameter. The number of parameters is either fixed or variable, depending
      on the control function. If the number of parameters is variable, neither the maximum number of values
      nor the order in which the corresponding actions are performed are defined by this Standard.
      A parameter may be purely numeric or it may be selective, i.e. denoting one of a numbered list of actions
      the control function can perform.
      ...
---

Each parameter substring represents one parameter.

---
5.4.2 Parameter string format
      A parameter string which does not start with a bit combination in the range 03/12 to 03/15 shall have the
      following format:
      a) A parameter string consists of one or more parameter sub-strings, each of which represents a number
          in decimal notation.
      b) Each parameter sub-string consists of one or more bit combinations from 03/00 to 03/10; the bit
          combinations from 03/00 to 03/09 represent the digits ZERO to NINE; bit combination 03/10 may be
          used as a separator in a parameter sub-string, for example, to separate the fractional part of a decimal
          number from the integer part of that number.
      c) Parameter sub-strings are separated by one bit combination 03/11.
      ...
----

So a parameter substring is 0-9 and the colon. The semicolon separates sub-parameters. Thus 48:5:<Color>
would be one sub-parameter, and 48;5;<Color> many independent, each having an independent meaning
in case of a selective parameter.

---
8.3.117 SGR - SELECT GRAPHIC RENDITION
        Notation: (Ps...)
        Representation: CSI Ps... 06/13
        Parameter default value: Ps = 0
---

Above, Ps... means variable number of selective parameters.

If they really do 48;5;<Color>, this is inconsistent, as it breaks the parameter concept cited above, at least
in my reading. So how to interpret e.g.?

ESC[48;5m ESC[39m
ESC[48m ESC[5m ESC[39m
ESC[39;48;49m


-lars