A zombie emoji? Yes, that's good. That has been approved and will most likely be coming to your phone and computer screen next year.

A scuba diver emoji? Maybe. That's on the list of draft candidates up for further debate.

But a woolly mammoth emoji? Not distinctive enough from the elephant, meeting notes indicate. A heart with a knife? "Unnecessarily violent." A "mic drop" emoji? "Could be too trendy".

These are the bizarre but crucial discussions that consume an obscure group of volunteer Silicon Valley software engineers who wield the ultimate influence over your text message humour.

Emojis were used in about 2.3 trillion mobile messages last year, according to the Emogi​ Research Group, and the little crying faces and smiley poos have become a cultural phenomenon, spawning movies and merchandise and becoming Oxford Dictionary's word of the year in 2015.

But the process of creating emojis is much less known; a fascinating process that is equal parts grassroots democracy and opaque Silicon Valley aristocracy.

For 26 years, the not-for-profit Unicode Consortium has set the standards for digital text by encoding languages so they appear the same across all digital platforms. About 7000 characters are added each year and Unicode debates the merits of each. Recently it was a new medieval punctuation mark and a character for the Konyak language of north-eastern India.

Yet in 2007, they took on the role of encoding emojis too. And as they have become a near-universal means of communicating – the emoji keyboard is on more phones than any language keyboard in the world, says Unicode member and Australian emoji guru Jeremy Burge – the decisions Unicode makes have taken on a political and cultural significance that few anticipated.

Why are all the female shoes high heels? Why are there no redheads? Why is there a flag for Brittany? Why are there so few Indian foods? Why is the gun emoji pointing back at the user?

The emoji criteria

The word "emoji" comes from the Japanese words e (picture), mo (writing) and ji (character) and began in the 1990s on Japanese phones. They proved popular but each mobile phone carrier developed different sets, meaning they were incompatible with one another and often got scrambled.

As emojis spread globally, Google began developing its own system to support their use across platforms but, realising that a private-use approach would not work, a proposal was made to Unicode to take over.

Unicode's membership list shows that those who have paid to join the consortium include the big tech companies, advocacy groups for language development and emojis, the University of California Berkeley's linguistics department and, rather strangely, the governments of Bangladesh and Tamil Nadu. 

However, almost every emoji starts with the general public. Anyone can submit a proposal for an emoji to Unicode's Emoji Subcommittee, which discusses them in weekly meetings and goes back and forth with proposers to refine them. Each quarter, the Unicode Technical Committee decides which proposals progress to a draft list. Major vendors like Apple, Gmail and Facebook have a big say.

Once a year, the UTC will release a final list of approved emojis, creating the code for each and a suggestion of how it might look. It is then up to vendors to incorporate some or all into their systems with their own aesthetic interpretation. The process, from proposal to release, takes about 18 months.

Unicode's 2600 emojis remain an open source, meaning anyone can use them without permission.

"Everyone loves emoji and yet no one company owns it. I think the fact it's an unbranded property has helped it become such a phenomenon," says Burge, who worked as a tech consultant for Australian universities before starting online emoji library Emojipedia five years ago and becoming vice-chairman of the Emoji Subcommittee.

Proposals will be seriously considered if they meet stringent criteria. There must be a high expected usage. For example, the successful proposal for broccoli (you'll most likely see that on your phone next year) by broccoli lovers Aviv Ovadya and Ashwini Oruganti showed that Google searches for the green vegetable far outrank those for grapes, eggplant and sweet potato, all of which already exist as emojis.

There should also be multiple possible usages (for example, a shark could also convey a loan shark or jumping the shark) and it should break new ground or be distinctive from existing emoji. If an emoji is frequently requested, it may add weight but Unicode says it will not be swayed by petitions or by emojis that further a cause, no matter how worthwhile.

Proposals are rejected if the emoji is overly specific (for example, multiple types of sushi), already representable (like the woolly mammoth), too transient or faddish (sorry, mic drop emoji) or contains any logo, brand, deity or specific person. 

Last week, at the UTC's quarterly meeting, a scuba mask, a Hindu temple and an oil lamp were added to the draft list.

"We try to balance the kinds of requests that come in. Part of our assessment is to ask: are we really breaking new ground? Are we really getting something that was impossible to depict beforehand?" said Mark Davis, chief internationalisation architect at Google and Unicode's president and co-founder. 

A "take a break" emoji depicting someone kicking back with a snack was recently considered, he said. "But it looked suspiciously like a Kit Kat bar being broken."

Then there was the taco proposal that fast-food chain Taco Bell threw its might behind. Regardless, the emoji had its own merits and was accepted.

But no matter how many unusual animals and foods are debated, the most common emojis rarely change. 

A real-time tracker of emoji use on Twitter shows that the laughing face with tears of joy is the most popular with almost 2 billion used since mid-2013, more than twice the red heart and the smiling face with heart eyes.

"The worst emoji is the customs declaration symbol," Davis said. "You never see that one, that's for sure."

Interestingly, Australia has distinct preferences. A 2015 study called Australia "the land of vice and indulgence" with double the global average use of alcohol-themed emojis and the biggest use of junk food and holiday emojis. In comparison, Canadians used the gun and sports emojis the most, French speakers used the heart four times more than other language speakers (and were the only ones for whom the smiling face wasn't No. 1) while Arabic speakers used four times as many flowers and plants.

The changing faces of emojis

Skin tone variations were recently added.

Unicode is largely guided by the proposals they receive and driven by data around usage, says Burge. But their decisions do not please everyone and, as emojis have exploded in popularity, representations of gender, religion, culture and politics have become the subject of intense debate.

"I think a lot of people see emoji as validation that you exist. People feel like, if they're not on the keyboard, they're not valid," he says.

In 2015, two friends campaigned for a dumpling emoji, arguing that Unicode was predominantly white, male engineers who were well-intentioned but had implicit biases. They formed a group called Emojination and have since become members of Unicode, helping marginalised groups to write proposals, like the successful girl in hijab emoji. Their dumpling was approved this year.

Burge says he gets the most requests for a red hair emoji. That's now on the draft list, as is a women's ballet flat shoe proposed by California arts publicist and mother Floriane Hutchinson, who started the #IWearFlats campaign after realising all women's shoe emojis were high heels, a likely hangover from the original Japanese collection.

"Although a flat shoe is not highly requested, it is due to broader social and cultural forces at play," she wrote in her proposal. "Implicit bias can lay dormant forever until there is a course correction made."

Skin tone variations were recently added and Burge says gender neutrality is a priority but they have to weigh up practicality.  "No one wants thousands and thousands of emojis on the keyboard," he says.

Then there are the left-field consequences that no one anticipates. Unicode is in the midst of discussing the literal direction of emojis, an issue highlighted by Jane Solomon, a lexicographer with dictionary.com, who said the direction of the gun (it points to the left) dictates its meaning.

She found that characters being shot were twice as common as characters doing the shooting, and she points to the case of a New York teenager who was charged – and acquitted – with threatening police for a Facebook status of the police officer emoji followed by three gun emojis.

The sensitivity around gun emojis is not lost on tech companies. Without explanation, Apple recently changed its to a green water pistol. And, for reasons that Burge would not disclose, a proposal for a rifle as part of an Olympic pentathlon series was suddenly dropped from Unicode's final list when vendors withdrew support. 

In the peculiar world of emoji creation, it was consigned to the dustbin. Rifles are out, zombies are in.