A non-combining form is U+02CDˍMODIFIER LETTER LOW MACRON. It is not to be confused with U+0320◌̠COMBINING MINUS SIGN BELOW, U+0332◌̲COMBINING LOW LINE and U+005F_LOW LINE. The difference between "macron below" and "low line" is that the latter results in an unbroken underline when it is run together: compare a̱ḇc̱ and a̲b̲c̲ (only the latter should look like abc).[2]
Unicode
Macron below character
Unicode defines several characters for the macron below:
Various precomposed letters with a macron below are defined in Unicode:
upper case
lower case
notes
letter
Unicode
HTML
letter
Unicode
HTML
Ḇ
U+1E06
Ḇ
ḇ
U+1E07
ḇ
Used in the transliteration of Biblical Hebrew into the Roman alphabet to show the fricative value of the letter beth (ב) representing [v], or perhaps [β].
Ḏ
U+1E0E
Ḏ
ḏ
U+1E0F
ḏ
Used in the transliteration of Biblical Hebrew, Syriac and Arabic into the Roman alphabet to show the fricative value of the letter dalet (ד), [ð], and in the romanization of Pashto, it is used sometimes to represent retroflex D. In Dravidian languages' transcription it represents an alveolar /d/.
Used optionally in the K-dialect of Māori in the South Island of New Zealand, where an original ng has merged with k. The ḵ indicates that it corresponds to ng in other dialects. There is no difference in pronunciation between ḵ and k.
Used in Pitjantjatjara to represent [ɳ], and in Saanich to represent both plain and glottalized[ɴ]. In the romanization of Pashto, it is used sometimes to represent retroflex N. In Dravidian languages' transcription it represents an alveolar /n/.
Ṟ
U+1E5E
Ṟ
ṟ
U+1E5F
ṟ
Used in Pitjantjatjara to represent [ɻ], and sometimes in the romanization of Pashto to represent the retroflex R. In Dravidian languages' transcription it represents an alveolar trill /r/.
Ṯ
U+1E6E
Ṯ
ṯ
U+1E6F
ṯ
Used in the proposed Unified Alphabet for Mapudungun language representing [t̪]. In the romanization of Pashto, it is used sometimes to represent retroflex T. In Dravidian languages' transcription it represents an alveolar /t/. In the romanization of Arabic this letter is used to transcribe the letter Ṯāʾ.
Note that the Unicode character names of precomposed characters whose decompositions contain U+0331◌̱COMBINING MACRON BELOW use "WITH LINE BELOW" rather than "WITH MACRON BELOW". Thus, U+1E07ḇLATIN SMALL LETTER B WITH LINE BELOW decomposes to U+0062bLATIN SMALL LETTER B and U+0331◌̱COMBINING MACRON BELOW.[3]
The Vietnamese đồngcurrency sign resembles a lower case d with a stroke and macron below: U+20AB₫DONG SIGN but is neither a letter nor decomposable.[4]
^"6.2 General Punctuation"(PDF). The Unicode Standard. Version 11.0.0. Mountain View, CA: The Unicode Consortium. 2018. p. 273. ISBN978-1-936213-19-1. Retrieved 2018-12-12. Spacing Overscores and Underscores. U+203E OVERLINE is the above-the-line counterpart to U+005F low line. It is a spacing character, not to be confused with U+0305 COMBINING OVERLINE. As with all overscores and underscores, a sequence of these characters should connect in an unbroken line. The overscoring characters also must be distinguished from U+0304 COMBINING MACRON, which does not connect horizontally in this way.