Unsupported titles/`lowbar`

_	U+005F, _ LOW LINE

Character variations

＿	U+FF3F, ＿ FULLWIDTH LOW LINE

Blinking cursor example.

_ (English symbol name underscore or underline)

Used to indicate a space to be filled in. Often, the symbol is used repeatedly to form a longer line.
Age: __ Gender: _

Sign here: _________________________________ Date: __________
(mathematics, in plain text) Separates a symbol with a subscript character, representing a variant of the base symbol.
Force is denoted with F. Centripetal force is denoted with F_c which may be written as F_c.
(computing) Used to represent what would normally be a space ] [ in computing.
My email address is jon_smith@example.com.
1. Used as a cursor to indicate a place where text can be typed. On visual display units, the underscore may be made to blink.
  MS-DOS prompt: C:\>_
2. (programming) Especially as a prefix: used to denote a special identifier such as a global or private variable or a reserved symbol.

_

Translingual