Man pages matching name xkbsaredirectsetvmodsmask in section 3:

XkbSARedirectSetVModsMask.3.en	debian 10 / libx11-doc
XkbSARedirectSetVModsMask.3.en	debian 11 / libx11-doc
XkbSARedirectSetVModsMask.3.en	debian 12 / libx11-doc