Creating custom yellow handshake emojis with zero-width joiners

Is there any specification on how "far" a zero-width joiner can reach? I thought a ZWJ would only affect the codepoints directly adjacent to it, but here we have sequence of 5 codepoints and only one ZWJ for all of them (which is also the only codepoint that signals that "special treatment" should be applied here).

So how would a parser know all five codepoints make up a grapheme cluster and not just the inner three?

Edit: Ok, didn't realize the "Fitzpatrick" codepoints are modifiers that I guess always refer to the previous codepoint. So there is essentially an "operator precedence" defined between modifiers and ZWJs.

I did a project in a similar vein for family emoji: https://familyemojimaker.netlify.app/ (https://gitlab.com/bettse/family)

Was curious whether the Zero Width Joiner was ad-hoc with anything provided, or a long list of specific combinations. Turned out it was specific combinations, and the list is rather impressive.

[1] https://unicode.org/emoji/charts/emoji-zwj-sequences.html#1f...

Unicode.org has a list of the recommendations [1]. It's somewhat long. Takes a bit to load. There's also a bunch that are "really" long. "man facepalming: medium-light skin tone" is great. U+1F926 U+1F3FC U+200D U+2642 U+FE0F Now I can do a Picard in Unicode. Now if only they had "man who is bald facepalming." Pretty sure that means adding U+1F9B2 somewhere, maybe U+1F468 U+200D U+1F9B2.

U+1F468 U+200D U+1F9B2 U+1F926 U+1F3FC U+200D U+2642 U+FE0F kind of works.

Also like U+1F9B9 U+200D U+2642 U+FE0F, "man who is supervillain". Current version looks more like Minions movie, and suggested sample looks more like "mime vampire who is stuck in plastic action figure container"

"Unicode is just too complex to ever be secure"

https://www.schneier.com/crypto-gram/archives/2000/0715.html...

Wise words from Bruce Schneier from 2000.