This style guide uses Australian spelling, as listed in the Macquarie Dictionary:

  -ise, as in specialise, organise (not -ize, as in specialize, organize)

  -our, as in colour, valour (not -or, as in color, valor)

  -l, as in fulfil, enrol (not -ll, as in fulfill, enroll)

  -ll, as in travelled or modelling (not -led or -ling, as in traveled, modeling)

Names of organisations retain their own spelling:

  World Health Organization    Jewish Defense League