International Currency Formatting Guidelines — Currency Codes

In developing a web application that presents monetary data for a variety of locales, I have inquired about the differences of currency formats. In particular, I'd like to know when it is appropriate to use currency codes, either in addition to or instead of currency symbols.

It's my understanding that all mainstream currencies require that a currency symbol be included, but some show them in different order (as seen on this website). The four currencies that I facilitate in my application are USD, CAD, GBP, and EUR — all of which have the same general currency format.

It makes sense to include the currency codes for USD and CAD, since they have the same currency code, but what about the others? What's the norm in these other countries?

Anyway, I have below what I think to be the correct formats. Please let me know if I have made any errors:

• United States  — $1,234,567.89 USD
• Canada           — $1,234,567.89 CAD
• Great Britain   — £1.234.567,89 GBP
• European        — €1.234.567,89 EUR

Also, should there ever be spaces between the currency symbols and the numbers? That is yet another thing I do know happens sometimes, but am not sure what the rules are.