Both spellings are valid, and one should not be replaced with the other unless a page uses both spellings, or if they appear in sample code but the code won't work with the used spelling (which should be a very rare occurrence).
Both spellings are valid, and one should not be replaced with the other unless a page uses both spellings, or if they appear in sample code but the code won't work with the used spelling (which should be a very rare occurrence).