I just learned about the DIN 47100 standard for wire colors, which includes pink. I thought it might explain why a certain vendor of hookup wire includes pink instead of grey in their 10-color kits (??). It does not, because DIN 47100 keeps grey and drops orange instead.

Not only did it not explain that thing I was wondering about, it laid eggs in my head and fed half my brain to its evil larvae. This page will likely serve no purpose beyond an attempt to exorcise myself.

DIN 47100: how did that happen?

Take a look at this train wreck:

• Let's ignore the three-color codes from 45 and up, which are apparently often ignored to favor repeating the 1-44 sequence.
• Starts with 10 solid colors — ok.
• The top dozen of the right column, 31-42, look perfectly systematic: pairs of green & yellow with blue stripes, red stripes, and black stripes; then pairs of grey & pink with the same stripe sequence. Blue, red, and black follow the sequence of solid colors as do green,/yellow and grey/pink.
• Yes, the code is often used for cables of wire pairs.
• But what about the left column? Three pair 21-26 look like the same kind of sequence as 31-36 and 37-42. Since white and brown precede the green-pink sequence it would make sense for 21-26 to precede 31, which they do, but not directly. And how to make sense of any of the rest of that?

What a mess.

It's clearly not random, but hints of regularity appear randomly distributed. How could that come out of Germany? To be fair, DIN "withdrew" the standard >20 years ago, but how did it live there from 1944-1998? And it lingers still — seemingly common in "LiYY" and "LiYCY" cables, of which I've learned nothing but to associate them with DIN VDE 0812 although the latter apparently does not specify color. (I say "apparently" because the standards are ̶ ̶j̶e̶a̶l̶o̶u̶s̶l̶y̶ ̶g̶u̶a̶r̶d̶e̶d̶ ̶d̶a̶r̶k̶ ̶s̶e̶c̶r̶e̶t̶s̶ ̶ ̶ paywalled.) 

I looked it up. Judging by the sources Google likes, DIN 47100 confuses everyone. Not only do different references disagree but some have internal inconsistencies. None are authoritative, so which is closer to right? Some of the confusion relates to variability of "standard" abbreviations which apparently weren't part of 47100.

• Wikipedia
  • apparently valid info
  • but not because supported by cited references
    • Colorhex ref is entirely completely irrelevant?
• igus (Wikipedia article reference)
  • does not include abbreviations used in the Wikipedia table for which this is cited as reference
  • code 28 "grey-yellow" text
    • reverse of "yellow-grey" in Wikipedia
    • but image shows yellow-grey
    • relevant because that's part of the mess
• Eland
  • includes abbreviations, but different abbreviations 
    • abbreviates brown inconsistently as BR & BN
  • code 28: "Yellow-Grey (YWGR)" (text only)
• CAE Groupe
  • image linked above
  • code 28: "Grey-yellow" text with corresponding image
    • internally consistent at least
    • correct? (apparently not)
• Belcom
  • abbrevs like Wikipedia, but:
  • code 17: "WHITE-GREY WH(ite)YE(llow)" - eh? (image is white-grey)
  • code 28: yellow-grey (with corresponding image)
  • code 34: YERD but image shows solid YE (gfx layers problem? looks like there is a red stripe behind the yellow ring)
• Mueller Group
  • um, sounds German...
    • but is US-based "stocking distributor of European-made" cable
  • no abbreviations, no pictures, i.e. no fluff
  • lists only 1-44 repetition, no 45+ three-color codes, but counted as 1-22 pairs
  • pair 14 (i.e. 28/2) core B: "Yellow/gray"
    • "grAy": shibboleth for US market
  • internally consistency looks encouraging
    • ...like but not in agreement with CAE Groupe, who are actually European

So who's right about the colors for 28/14B? Further digging in more places turns up more votes for yellow-grey than for grey-yellow, so maybe Mueller Group, and Wikipedia, have the colors right. That's colors - not touching abbreviations.

And then there's Helukabel — bona fide Germans — who, according to a Helukabel reference page hosted by Sealcon Cable & Wire (formerly Hi-Tech Controls and not rushing to change their domain), appear to suggest that DIN 47100 actually specifies only repetition of 1-44 sequence "according to DIN 47100" and calls the 45+ three-color codes an "adapted" "deviation to DIN".

And violet is used only once for "10" and never again in the multi-color jumble-code.

So who knows what the standard actually says? The actual standard might even include a rational rationale for the chaotic coloration. I don't care enough to give €30 for a look at a "withdrawn" standard. It seems like there would be some dead tree copies lingering in libraries, but I didn't succeed at finding any in WorldCat.

Color abbreviations

Colors, if not their meanings, and abbreviations apparently have become pretty well nailed down by agreement of BS 7645, IEC 60757, and CENELEC HD 457 — all of which are, again, secret. Again, Helukabel via Sealcon looks fairly likely to have the valid info:

black	BK
brown	BN
red	RD
orange	OG
yellow	YE
green	GN
blue	BU
violet	VT
grey	GY
white	WH
pink	PK
turquoise	TQ

In other words, Wikipedia apparently has it right if unsubstantiated. And what source is there to cite?

What is the deal with secret standards? In the third decade of the third millennium, anyhow. I get that distributing material instantiations of documents around the world from a single or few points of manufacturing them from pulverized trees was the economical way to distribute information for much of the latter part of the previous millennium and someone had to pay for that. But none of this comes from the Society for Creative Anachronism. I get that standards bodies need operating cash. I can imagine that anyone with enough liability exposure to warrant paying for legal counsel might get counseled to shift liability by paying relevant standard organizations for artifacts that said organizations warrant to be complete and correct representations of their standards. But I don't get how preventing dissemination of information "for reference only" promotes promulgation of standards. "Do it our way." "Ok. What is your way?" "Our way is secret, until you pay us to show you, and promise not to tell anyone else see what you see, subject to enforcement."

?.

Dissected

Considering only the first 44 (or 22 pair) color combinations.

The mess starts with a benign series of 10 solid colors. The rest of 11-44 have two colors: a base color with a stripe color.

Ignore 11 & 12. For now.

For the remaining two-color combinations, 13-44, each odd-even pair have one color in common. For the runs 21-26 and 31-44 it's the stripe color. In other pairs the common color is the stripe of one, either first or second, and base color of the other of the pair. In effect each pair uses three colors, as some irregular combination of base and stripe colors.

The pair-wise combinations of three colors do actually make sense. Mostly. Considered as numbers, because I don't naturally think of colors as ordered, the combinations look like: 

pairs of	with "higher" third colors
1 (white) & 2 (brown)	3,4,5,6,7,8,9
3 (green) & 4 (yellow)	5,6,7,8,9
5 (grey) & 6 (pink)	7,8,9
7 (blue) & 8 (red)	9

Ok. That seems like a sensible rule for pair-wise generating unique three-color combinations, such that each pair share a common color and consecutive pairs have different common colors (mostly, up to the last pair of pairs: GYBK/PKBK & BUBK/RDBK). In this scheme the common color of each pair is always the "highest" order of the three colors.

But what about which color is primary/base color or secondary/stripe for any given wire?

It would make sense either for pairs to share a common base color with different stripe colors, or to share a common stripe color over different base colors. Either way and 47100 does the latter. I suppose it might have depended on whether the sequence of pairs or polarity within pairs was considered more "significant". In a vacuum, I'd have given pair identification greater significance but can imagine that when ripping through some operation with a bunch of pairs, I'd appreciate visual emphasis on polarity within each pair. Especially if pairs are already obviously pairs because twisted. Whatever. Or presentation of colors could have been specified as explicitly arbitrary, so long as two colors were shown. Any of pair-wise common stripes over different base colors, or different stripes over common base colors, or unspecified presentation of specified color pairs would have made sense. Specified randomness doesn't make sense.

The standard does appear to favor pairs with a common stripe color over distinct base colors: 11 instances vs 0 pairs with common base color.  So let's suppose that common stripe colors over pairs of distinct base colors would have best served whatever purposes shaped 47100.  

What, then, was up with the pairs that reverse the base/stripe coloration of one of the pair?

The irregular pairs (above 12) fall into two groups.

First: the 2nd, 3rd & 4th of the 7 {white,brown}+color pairs. In those pairs, white (odd codes) is always the base color. It's brown (even codes) that's sometimes the base color (4/7) and sometimes the stripe color (3/7). Brown is the base when the stripes are a primary color or black. Brown is the stripe when the other color is a very light color (yellow) or de-saturated (grey, pink). So maybe they wanted to avoid expecting people to distinguish a light or de-saturated stripe color over a dark saturated base color. ?.

Second (and, apparently, wrong in the image above): the first two of the five {green,yellow}+color pairs. Igus (Wikipedia's reference) and CAE Groupe (pretty picture above) say wire 28 is grey with yellow stripe. Eland, Belcom, Mueller Group & Helukabel  say 28 is yellow with grey stripe. I'm guessing the latter more likely reflects what the (former) standard would say if it wasn't (still) a guarded secret. Supposing so: yellow (even codes) is always the base color while green (odd codes) is sometimes the base color (3/5) and sometimes the stripe color (2/5). Green is the base color when the stripes are a(nother) primary color or black. Green is the stripe color when the other color is de-saturated (grey, pink). So, again, that may have been done to avoid expecting people to distinguish a de-saturated stripe color over a saturated primary base color.

I skipped over 11 & 12.

The two-color codes 13-44 use four pairs of colors opposite each each other to distinguish the two wires of each pair, so no one wire uses the two colors of one of those pairs together. Codes 11 & 12 use two of those available pairs: 5(grey)/6(pink) and 7(blue)/8(red).

Although these two codes come before all the other two-color codes in sequence, it appears that they were assigned from colors left over after systematically generating all the following three-color pairs of two-color combinations. Assuming codes earlier in sequence are used more often than codes later in sequence, it seems like it would have made better sense to use the systematically generated color combinations in sequence before the irregular leftovers. 

The standard maintains consistency in specifying irregular assignments of base and stripe colors. Because the 11 & 12 codes pair two de-saturated colors and two saturated primary colors, the apparent saturated-over-desaturated practice suggested above does not apply for these two codes. Between the two de-saturated colors, using the "higher" order color 6(pink) to stripe over a 5(grey) base follows the pattern of "higher" order colors striping over "lower" order colors where not contraindicated by visibility expectations. Where it seems the two saturated primary colors could be assigned in either orientation, and so could follow the higher-stripes-lower pattern for the 12 code, they do not. Why not? Just for lulz to stir a little more confusion into the last decision?

Maybe they had reasons. Did anyone take notes?

Reconstructed

Given:

• the ordered set of ten colors,
• the basic scheme for generating three-color pairs of two-color codes after the first ten, and
• apparent preference for pairs to have distinct base colors with a common stripe color,

it seems to me that DIN 47100 could have been done quite sensibly if they weren't in such a hurry to get to the bar, or otherwise confounded by some undisclosed distorting constraint.

Given that, within the systematically colored range 13-44, the common color of a pair is always the "higher" order color, and the 47100 perpetrators apparently preferred for the common color to stripe the distinct colors, it seems to me that their major problem was simply the order of the first 10 solid colors. If yellow, grey and pink can't stripe over brown, move them "under" brown.

A simple shift would yield the order: white, yellow, grey, pink, brown, green, blue, red, black, violet.  Or, pair-wise: {white,yellow}, {grey,pink}, {brown, green}, {blue,red}, {we see no fifth pair...}.  That would avoid all the base/stripe reversals of DIN 47100.

However, that pairs white and yellow, which may have less contrast than the current combinations. Also, while grey & pink were already paired, that amounts to pairing partially de-saturated red with fully de-saturated red, which may be less than ideal contrast for some color variations in some lights. Rotating the three shifted colors to put yellow above the de-saturated colors would yield the sequence white, grey, pink, yellow, brown, . . . , and pairs {white,grey}, {pink,yellow}, {brown, green}, {blue, red}, {nope, still no fifth pair...}.

The new pair of brown and green should be no problem. 

With that re-ordering, the color combination sequence look like this: 

pairs of	with "higher" third colors
1 (white) & 2 (grey)	3,4,5,6,7,8,9
3 (pink) & 4 (yellow)	5,6,7,8,9
5 (brown) & 6 (green)	7,8,9
7 (blue) & 8 (red)	9

And that avoids the cases where the 47100 committee apparently felt need to switch base and stripe colors.

About the irregular 11 & 12 combinations... well, wait, what about violet? Why ever not use the color you're already using, especially when you think you're out of colors?‽! Forget bodging in a couple more irregular combinations when we can get eight more, that's four pairs, that make perfectly good sense?

pairs of	with "higher" third colors
1 (white) & 2 (grey)	3,4,5,6,7,8,9,10
3 (pink) & 4 (yellow)	5,6,7,8,9,10
5 (brown) & 6 (green)	7,8,9,10
7 (blue) & 8 (red)	9,10

Abandoning omission of the obvious gets, in addition to orderly progression of color combinations:

• well, actually use that one color we're already using anyhow!
• bodges? we don't need no steenking bodge combos
• consecutive striped pairs ̶ ̶a̶l̶m̶o̶s̶t̶ ̶ ̶ always have different common stripe colors
• net three more pairs (+4-1) gets up to 25 pair — Bell System 25 pair cable prolly wasn't a thing yet in 1944, and DIN and Bell prolly weren't on speaking terms at the time, but base 10 counting was pretty well established and 4x25 gets conveniently to 100 which rolls up nicely to bigger numbers

So with the same ten colors, basic color encoding scheme and apparent constraints evident in DIN 47100, the committee could just as easily, if not more easily, come up with a perfectly orderly 25-pair color code like:

But they didn't. Does the actual DIN 47100 doc, in any version, say anything about why they did what they did? If not, has such knowledge survived in any form?