Image copyright Bangkok University Image caption The uniforms Bangkok University said it had approved for "ladyboys" - the trousers are slimmer than male students'

One of Thailand's most prominent universities has issued new guidelines for uniforms.

Nothing really new there; Thai universities usually require students to wear an approved uniform.

But the new illustrations published by Bangkok University are for transgender students, showing how either "ladyboys" or "tomboys" can dress according to their chosen gender and still stay within the official dress code.

Transgender people are unusually visible in Thailand, where the annual Miss Tiffany transgender beauty contest is a national event, and people come from all over the world for gender reassignment surgery.

Image caption Third gender toilets were installed in this school in Isan, in rural Thailand

Some high schools have built "third gender" toilets for pupils who do not feel comfortable in either the men's or women's facilities.

However, they are not allowed to change the gender on their national ID cards, leading to awkward scenes at the annual army service draft for young men every year.

Even those who now have women's bodies are required to attend a physical examination for the ID card before being rejected, sometimes on mental health grounds.

So the Bangkok University move has been welcomed as a step towards full acceptance of transgender students.

"I am very glad to hear that this university lets the students choose the uniform which fits their desire and their gender," said Nok Yollada, President of the Transgender Female Association of Thailand.

Image copyright Bangkok University Image caption The uniforms Bangkok University said it had approved for "tomboys" - the trousers are a looser fit than for male students

Poy Treechada, a renowned transgender actress, also welcomed the move, saying she felt transgender students would earn more respect from society if they were seen to be respecting the university's rules.

As for the university, it offers a more prosaic reason for its new guidelines.

In a statement accompanying the illustrations, it said it was simply trying to maintain the dress code.

Too many transgender students, unwilling to don the clothing that matched their official gender, were wearing whatever they liked, it said.

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The rules on uniforms at university have often been criticised as enforcing conformity and submissiveness on Thai students.

Image copyright Getty Images Image caption The traditional Thai university uniform for women, worn here as they await the arrival of the Norwegian royal family in 2004

Two years ago, one transgender student at Thammasat University, which is unusual in that it does not generally require uniforms to be worn, took her protest to a new level by distributing images of herself, in uniform, in sexually provocative poses.

Saran "Aum Neko" Chuichai was later charged with lese majeste, or insulting the monarchy, and fled into exile after last year's military coup.

But her unusual protest reignited the debate over university uniforms.

An opinion poll published shortly afterwards suggested that more than 90% of students believed uniforms were necessary to maintain order.

At Bangkok University, at least, they can now choose which gender of uniform they prefer.