GLYPH_UNKNOWN_FLAG

pango

Constant GLYPH_UNKNOWN_FLAG 

Source 
pub const GLYPH_UNKNOWN_FLAG: Glyph = ffi::PANGO_GLYPH_UNKNOWN_FLAG; // 268_435_456u32
Expand description

Flag used in PangoGlyph to turn a gunichar value of a valid Unicode character into an unknown-character glyph for that gunichar.

Such unknown-character glyphs may be rendered as a ‘hex box’.