Obliquely ground nibs (oblique, abbreviation 'O') produce a broader script with narrower vertical strokes and react very sensitively to hand position; at the wrong angle the nib scratches or skips. There are considerable differences between OF and OB, so extensive writing samples before purchase are important. For very flowing signatures these nibs are not ideal, but they can be used optimally by lightly turning the pen (counter-clockwise so the oblique foot lies parallel to the paper) — this gives maximum line variation. A detailed English-language guide is available in an article on richardspens.com. Signatures with a ballpoint are regarded among collectors as a stylistic faux pas.