Converts the visible ASCII characters — letters, digits and punctuation — plus the space between their normal half-width forms and their full-width (fullwidth) counterparts in the range U+FF01–U+FF5E. Full-width forms take up the same box as a Chinese character, so they often sneak into Chinese typography.
Use “To half-width” to normalise stray full-width English letters, numbers and symbols back to plain ASCII, or “To full-width” for the reverse. Only ASCII-range characters and spaces are touched; everything else is left unchanged. All conversion runs locally.