The types of glyphs used by bullets when paragraphs at this level of nesting are ordered.

GLYPH_TYPE_UNSPECIFIED The glyph type is unspecified or unsupported.
NONE An empty string.
DECIMAL A number, like 1, 2, or 3.
ZERO_DECIMAL A number where single digit numbers are prefixed with a zero, like 01, 02, or 03. Numbers with more than one digit are not prefixed with a zero.
UPPER_ALPHA An uppercase letter, like A, B, or C.
ALPHA A lowercase letter, like a, b, or c.
UPPER_ROMAN An uppercase Roman numeral, like I, II, or III.
ROMAN A lowercase Roman numeral, like i, ii, or iii.