Gwoyeu Romatzyh is a fairly complex Romanisation. Instead of using diacritic marks or appended digits, the creators decided to give each syllable-tone combintation a distinctive shape. So syllable guo (e.g. 国, 果) becomes guo, gwo, guoo, guoh for tones one to for.

This is actually the most prominent feature GR is known for. By the way, I believe it is mostly abbreviated as it's difficult to remember the correct spelling Gwoyeu Romatzyh, which itself comes from Guóyǔ Luómǎzì, "National Language Romanization", and would be strictly rendered as Gwoyeu Luomaatzyh in its own system.

While this kind of spelling seems highly complex, Yuen Ren Chao, one of its creators, argues that with the tone included in the syllable itself, the learner is forced to also learn the tone at the same time - stressing its importance for pronunciation.

There is another factor though special to GR. Chao uses a lot of abbreviations in his books on GR, substituting for example i.geh (yī ge, 一个, "one") with ig, or chi.tzyy (qīzǐ, 妻子, "wife") with chitz. This is convenient for the writer, but for conversion to other Romanisations this is a major obstacle. Below I want to give a list of abbreviated forms I came across in Chao's books.

In some special cases it is even unclear if the spellings he used aren't merely ad-hoc forms, for example j-h-eh, a form of jeh said with laughter.

List of abbreviated spellings

Yuen Ren Chao: A Grammar of Spoken Chinese. University of California Press, Berkeley, 1968, ISBN 0-520-00219-9, pp. xxx, xxxi.

• a for .a (啊)
• ba for .ba (吧 and 罢)
• bu for bu, bwu, buh (不)
• de for .de (的)
• g for ₒgeh (个)
• i for i, yi, yih (一)
• ia for .ia (呀)
• j for -.jy, -.je (着)
• le for .le (了)
• ma for .ma (嗎)
• me for -.me (么) and .me (嚜)
• men for -.men (们)
• ne for .ne (呐)
• sh for ₒshyh (是)
• tz for -.tzy (子)

Yuen Ren Chao: Mandarin Primer: an intensive course in spoken Chinese. Harvard University Press, Cambridge, 1948.

• -tz for .tzy (子)
• -j for -.jy and .je (著)
• g for -.geh (個)
• de for .de (的)
• sherm(.me) for shern.me (甚麼) (p. 123)
• tzeem(.me) (怎麼) (p. 123)
• tzemm(.me) (p. 123)
• nemm(.me), also .ne.me (那麼) (p. 123, 138)
• jemm.me (simmilar to tzemm.me) (這麼) (p. 137)

The following forms have yet to be evaluated:

• V bu V for V .bu ₒV (pp. xxxi, first book)
• -.men as in 我們 and 你們 etc. turns to -m before labials (p. 123, second book)
• .èh (p. 22, 124), .oh (p. 22, 130), è (p. 153, second book) interjections
• j-h-eh (jeh), tz-h-uoh (tzuoh) meng, (p. 162, second book) marking laughter
• ss (p. 190, second book)

For an up-to-date list and license see http://code.google.com/p/cjklib/source/browse/trunk/cjklib/data/grabbreviation.csv.