Clarification about using "import"

I have a question about using the "import" tag - if in target namespace
"xyz" you want to reference a global element in namespace "other", do
you need to use the "import" tag, or is declaring the "other" namespace
in the "xyz" target schema declaration sufficient.

I realize that you would need to use the "import" tag to reference user
defined types in the "other" namespace - it just wasn't clear if
"import" was required for referencing ONLY global elements.

ingrid cenkl