[HansTWN]

Ahi, that article contains quite a bit of nonsense. You cannot write Taiwanese in "bopomofo", only Mandarin. You can write Taiwanese phonetically using the "TongYong PinYin", just as you can write Mandarin in that PinYin version or the regular PinYin. But the regular written language of Taiwanese, Cantonese and every other Chinese language is Hanzi.

"Cantonese is unique among non-Mandarin regional languages in having a written colloquial standard" -- I am sure what he is referring to is exactly what I have pointed out. Some special characters unique to Cantonese and sometimes a different syntax. An example (not a very nice one, but it will suffice) would be:

Mandarin "我把這個給你" "Wo ba zhe ge gei ni" Wo = I; Zhe ge = this thing, Gei = give, Ni = You. The use of "Ba" is a special construction needed in Mandarin when forming this sentence.

Cantonese "我給這個你" "Wo gei zhe ge ni" (Mandarin pronunciation of these characters). Actually most Cantonese speakers carry this over into Mandarin, but in Mandarin it is wrong. Sometimes different words are used. In Mandarin "電梯" "Dian Ti" stands for both escalator and elevator. In HK they use the same for escalator, but "升降機" "Sheng Jiang Ji" (literally = the machine that goes up and down) for elevator.

But it is written in Hanzi and can be easily understood by any Chinese reader (even by some 80 year-old in Taiwan who grew up learning only Taiwanese and Japanese, never even learning Mandarin). Just a few minor differences, but more pronounced than for other Chinese languages. Chinese when they communicate in writing always communicate in Hanzi , no matter what dialect they use. But when they read it out loud it becomes Cantonese, Taiwanese or whatever.