Fusible link questions

Both spellings are used in Canadian (+British, Australian, South African, Irish) English. "Practise" is usually the verb -- you practise the piano, you practise medicine or law. "Practice" is usually the noun -- you got some practice in before lunch, you have a law practice. But both spellings can be used for both, which is a good thing, considering I broke the convention and used "s" instead of "c" for the noun in my post above.

In American English, "practice" is used for both noun and verb.