For some, it is an annoying part of form-filling, though for most others it comes as no big deal. That is the part of Singapore forms that asks you to categorise yourself as either Chinese, Malay, Indian or Others.

The classification, commonly known by its acronym CMIO, is one where the Government categorises people - be it citizen, permanent resident or work permit holder - into one of these four racial groups.

Residents have been classified by race ever since the first census in 1824.

One bugbear has been that the rigid model glosses over the increasing diversity of a Singapore with more mixed marriages and immigrants.

It ignores the cultural differences between Singaporean Chinese and mainland Chinese, for example.

National University of Singapore social anthropologist Lai Ah Eng points out that some local Chinese find they have hardly anything in common with newer Chinese immigrants. She and other observers also feel that Singaporeans of various races often find they have more in common among themselves than with more recent immigrants from similar ethnic backgrounds.

There have also been concerns that it is dehumanising to be lumped under the broad "Others" category, which ignores the rich heritage and diversity of those who do not squarely fit into the Chinese, Malay or Indian groups.

Sociologists tell Insight that the CMIO model is potentially constraining as it pigeonholes people and, to a certain extent, perpetuates racial stereotypes.

Institute of Policy Studies (IPS) sociologist Mathew Mathews adds that the model creates expectations of how to fulfil one's identity as a person who is "supposed to be a member of one of the racial groups".

RELIC OF COLONIAL PAST

The CMIO model is a relic of Singapore's colonial past when British rulers dealt with diversity by assigning residential districts to respective ethnic groups, and generally splitting labour along ethnic lines.

Some argue the CMIO model is now irrelevant in an increasingly diverse Singapore, even as it was modified in 2011 to allow double-barrelling for Singaporeans of mixed parentage.

Inter-racial marriages have been rising. Last year, they comprised 20.4 per cent of 28,400 marriages, compared to 13.1 per cent a decade earlier. Singapore also takes in between 15,000 and 25,000 new citizens yearly.

As Singapore becomes more cosmopolitan, the proportion of "Others" is also increasing and brings with it its own challenges, as members of different groups seek to be identified on their own merits rather than labelled as one of the three main ethnic groups, let alone "Others".

However, experts caution against discarding the framework entirely, defending the model as necessary to give tacit recognition to minority communities of their distinct cultures, religions and languages.

Associate Professor Eugene Tan of Singapore Management University's law school, who has done research on ethnic relations, points out: "Due recognition is, ultimately, a vital human need and an important political and legal measure; it's not just a courtesy owed to the racial groups."

But Dr Nazry Bahrawi, a humanities lecturer at the Singapore University of Technology and Design, disagrees, and argues that the CMIO model should be banished, saying its drawbacks outweigh any potential advantages.

Removing it does not necessarily mean that race is no longer important, nor make minority groups anxious, he stresses. That is, if Singapore is "serious about preserving diversity in all its manifestations and uphold the importance of equal cultures".

Then again, thought leader Ho Kwon Ping, who was the first IPS S R Nathan Fellow, said in an April lecture that the CMIO's rigid racial categories should be "consciously blurred or even abolished", as they reinforced stereotypes.

But Mr Ho rescinded his opinion that the CMIO model should be abolished at a panel last month held by sociopolitical website Inconvenient Questions.

This came as several of his minority friends told him that, were the CMIO model abolished, they were worried about a situation where "the Government says, we are all one happy people, let's not talk about the need to send a signal that there is a Malay minority and an Indian minority".

Immigration has exacerbated these issues.

While the Government has been conscious about maintaining a relatively stable ethnic balance, there are concerns among some in the Malay community, aired at grassroots dialogues, that their proportion of the population is slipping.

Latest data for the resident population - which comprises Singapore citizens and permanent residents - show they make up 13.3 per cent of the population this year, down from 13.9 per cent in 2005.

Comparatively, the proportion of Indians rose from 8.4 per cent to 9.1 per cent, and those in the "Others" group went from 2 per cent to 3.2 per cent.

However, the mix of citizens has remained relatively stable - 76.2 per cent Chinese, 15 per cent Malay, 7.4 per cent Indian and 1.4 per cent Others.

A MORE NUANCED APPROACH?

But regardless of whether CMIO stays or goes, experts who spoke to Insight agree a more nuanced approach is needed, as opposed to the "uncritical" collection of data based on ethnicity.

Prof Tan, a former Nominated MP, notes that collecting ethnic-based data can provide a pulse of how the different groups are faring. But he questions the release of annual data of how different ethnic groups perform at national examinations, which he says can lead to unintended consequences like the reinforcement of racial stereotypes.

He says: "Would a Chinese professional household face the same educational issues as a Chinese household on public assistance? Probably not. The latter household is more likely to have more in common (with) a non-Chinese household on public assistance." .

And Dr Nazry says: "A number of such surveys have positioned Malays as the most problem-riddled group - high divorce rates, weakest academic performance and most susceptible to obesity."

Such issues, he adds, are better gauged using metrics such as socioeconomic status and household incomes, rather than ethnicity.

Chua Chu Kang GRC MP Zaqy Mohamad says removing references to race will not make any difference, especially as ethnic minorities will still be identified by names or skin colour.

"You can't run away from your background," he says, pointing out that while the United States has its first black President, it still sees heightened unrest due to race in areas such as Ferguson, after an unarmed black teenager was shot dead by a white policeman.

"It shows the divide is still there, no matter how hard you try to hide the race aspect."

Observers say above all, the retention of the CMIO model should never impede the building of a strong, shared Singaporean identity.

"Instead of pulling out the old chestnut of CMIO, let's see how we can further strengthen our civic identity and loyalty as Singaporeans," says Prof Tan.

Mr Ong Ye Kung, now Acting Minister for Education (Higher Education and Skills), also wrote in a commentary in April that people should look beyond labels, be it "Singaporean" or "CMIO".

But this does not mean "CMIO" is no longer relevant, he added.

"The truth is no label can adequately capture the complex essence of a person, nor is it meant to," he wrote. "My label as a Singaporean is inadequate in describing who I am as a person. Likewise, being CMIO cannot be an adequate description for a stronger national identity, but that does not mean it should be de-emphasised or discarded."

He added: "We are better off if we respect and appreciate each other for all our rich diversity, treating everyone as equal, striving for a common destiny. As members of our respective community, we are also citizens of Singapore, with a lifetime of common experiences, creating an identity as one united people."