H̱ (Unicode)
ẖ (U+1E96 "latin small letter h with line below", canonically equivalent to ẖ (U+0068 U+0331).
Note that Unicode does not reserve a codepoint for a "latin capital letter H with line below". Therefore, a sequence with a combining diacritic "macron below" must be employed: H̱ (U+0048 U+0331)). This lack of a precomposed character may pose a problem for some layout engines.
ẖ transliterates:
Because of a lack of a dedicated capital letter, version, the letter is often used in its place, particularly for Arabic transcription.