Macao SAR (SAR stands for Special Administrative Region)—written 澳門特別行政區 or 澳門特區—is in the process of standardizing MSCS (Macao Supplementary Character Set or 澳門增補字符集 in Chinese), which is character set standard that is designed as a supplement to HKSCS (Hong Kong Supplementary Character Set), and by extension, as a supplement to Big Five. One reliable source told me that MSCS can be described as HKSCS plus approximately 150 additional characters.
There are a small number of components whose forms differ from HK conventions, in terms of ideographs that are common with HKSCS, to include Big Five. The preliminary information that I have seen indicates that the following components follow TW conventions: 次 (versus 次 for HK), 女 when used as a left-side component (such as in 好), 粵, 亦, 告 instead of 吿 (such as in 造), 香, 木 when used as a bottom component (such as in 榮), 䍃 (such as in 猺), 啚 (such as in 鄙), and 肉 when used as a bottom component (such as in 骨). Interestingly, it seems that the KR form of the component 关 is used (such as in 咲). The image below includes ideographs that contrast the MO (top) versus the HK (bottom) forms for most of the affected components:
In an effort to prepare to properly support Macao SAR as a third form of Traditional Chinese in the Source Han Sans and Source Han Serif typefaces, along with the Google-branded Noto CJK ones, the open source Variable Font Collection Test project includes three Variable Font Collections (aka OpenType/CFF2 Collections), along with their 12 component Variable Fonts (aka OpenType/CFF2 fonts), that support Macao SAR in two key ways: the 'name' table strings in the fonts whose default region is MO—the two-letter region code for Macao SAR—specify 0x1404 as the Language ID, and the 'locl' (Localized Forms) GSUB feature uses the soon-to-be-registered 'ZHTM' language tag.
In closing, I need to clarify that there are no immediate plans to support Macao SAR as a third form of Traditional Chinese in the Adobe- and Google-branded open source Pan-CJK typefaces, but it is something that I eventually plan to do. Still, no action can be taken until the MSCS standard is published, at least in terms of font development. Font development will also involve supporting the 21 IVSes in the MSARG IVD Collection, along with the appropriate glyphs. With regard to 'name' table and 'locl' GSUB feature support, testing can start now, thanks to the open source test fonts that I made available.
P.S. In the process of writing this article, I learned that the currency used in Macao SAR is called the Macanese pataca, and instead of using a special symbol to represent it, the four characters “MOP$” are used.
P.P.S. The Source LOCL Test OpenType/CFF Collection test font serves as an ideal vehicle for testing support for Macao SAR in apps and other font-consuming environments.