Subject: [calsify] Proposed Errata for RFC 7986: COLOR property with arbitrary RGB values

From: Дилян Палаузов <[email-masked]>
Date: Thu, 28 Jun 2018 22:04:54 +0000

Hello,

I would like to suggest the following Errata and welcome any comments
within a month.

My reading is that COLOR now cannot have the value RGB(61,211,68)

Please correct me, if I am wrong.

RFC 7986 (new Properties for iCalendar)  Section 5.9. COLOR Property
says:
https://tools.ietf.org/html/rfc7986#section-5.9

Type: Technical
Section: 5.9 COLOR Property

Origianl text:

Description:   ...The value is a case-insensitive color name taken from
the CSS3 set of names, defined in Section 4.3 of [W3C.REC-css3-color-
20110607].

Example:  The following is an example of this property:
   COLOR:turquoise

Corrected text:

Description:   ...The value is either a case-insensitive color name
taken from the CSS3 set of names, defined in Section 4.3 of [W3C.REC-
css3-color-20110607], or an RGB() functional  notation with absolute
values specified in Section 4.2.1 of the same document

Examples:  The following are examples of this property:
   COLOR:turquoise
   COLOR:rgb(61\,211\,68)

Notes for the errata:

draft-daboo-icalendar-extensions-07 removed the possibily to have RGB
colours for COLOR.

CSS3 included color names, that browsers at that time suppored,
originating from X11's rgb.txt.  The color names and values were
randomly chosen.  The minimal distance between the colors isn't
consistent.  One motivation for creating a color name were hardware
capabilities - an argument which isn't valid for 20 years now.  There
is no reason to limit the number of possible values for COLOR.  A user
interface for choosing a named color has either to offer the user the
possibility to choose from a pre-filled list of colors, which could
clutter the interface, or let the user choose any RGB color and narrow
it later to the closest color with CSS3 name.  This narrowing isn't
trivial and performing it seems like having an RFC running in itself.

Notes for this message, outside the errata:

Gnome Evolution recently added support for the COLOR property and
uploaded iCalendar files by it now have:
COLOR:rgb(61\,211\,68)

https://www.w3.org/TR/2011/REC-css3-color-20110607/ lets also other
forms:
#f00
#ff0000
rgb(100%, 0%, 0%)

I have no propbem to let or exclude any of the forms above.  The main
challenge is neither to have the user chose from a final list of
colours, nor to let her choose any colour but narrow the selected
colour afterwards to something.  Letting more than one form of the
mentioned above would be overengineering for the mentined challanage.

https://github.com/w3c/csswg-drafts/issues/2813 states the colours are
chosen randomly, and http://christopher.org/history-web-color-names/
proves this thesis.

Randomly choosen colour values (having names coming from rgb.txt) are
not suitable to achieve any aim.

I haven't worked with colour terms until today, so feel free to
rephrase the rgb-functional sentence.

Regards
  Дилян

---

From: Neil Jenkins <[email-masked]>
Date: Fri, 29 Jun 2018 03:12:02 -0400

I wasn't involved in the original discussion, but I have a vague recollection from seeing the emails go by that this was intentional: the theory was clients are not going to use the actual colour you specify as they will want to pick something that goes with their branding + background + event display design, so by using names they could then choose their "version" of the colour that was closest in spirit to the name given.

Not sure I agree with this reasoning, but I think that was the idea.

Neil.

---

From: Andrew Laurence <[email-masked]>
Date: Fri, 29 Jun 2018 09:08:20 -0700

Users use colors to represent all sorts of known-to-them metadata. They care *deeply* about color assignment and fidelity.  When we moved from a calendar system that let users assign colors according to criteria (Boss is organizer? Red! Description contains "Lunch"? Green!) to one that didn't, I heard about it for *ten* years.

While preparing for the June 2017 CalConnect, I surveyed users about issues with calendars.  It came up *again*, in the context of wanting to choose colors and have them remain the same across clients.

-Andrew

> On Jun 29, 2018, at 12:12 AM, Neil Jenkins <[email-masked]> wrote:
> 
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