! # xmodmap -pk | grep -E 'XF86Forward|XF86Back'
!    166         0x1008ff26 (XF86Back)   0x0000 (NoSymbol)       0x1008ff26 (XF86Back)
!    167         0x1008ff27 (XF86Forward)        0x0000 (NoSymbol)       0x1008ff27 (XF86Forward)
! # xmodmap -pk | grep -E 'Prior|Next'
!    112         0xff55 (Prior)  0x0000 (NoSymbol)       0xff55 (Prior)
!    117         0xff56 (Next)   0x0000 (NoSymbol)       0xff56 (Next)
!
! mapping PgUp/PgDn to XF86Back/XF86Forward:
keycode 166 = Prior
keycode 167 = Next

! making XF86Back/XF86Forward duplicates of Left/Right keys:
! keycode 166 = Left
! keycode 167 = Right
