Man pages matching name qwtcpointerdata in section 3:

QwtCPointerData.3.en	debian 10 / libqwt-doc
QwtCPointerData.3.en	debian 10 / libqwt5-doc
QwtCPointerData.3.en	debian 11 / libqwt-doc
QwtCPointerData.3.en	debian 12 / libqwt-doc