Minor off-topic English orthographical explanation:

to PRACTISE: verb
a PRACTICE: noun

Easy to remember, Noun starts with N and verb with V.
N is earlier than V in the alphabet as the C in Practice the noun is earlier than the S in Practise the verb.

Re US spelling: this is often the much earlier, Elizabethan spelling rather than the more modern English usage.
Would have thought that, logically, WAV would have preferred this.