The IE7 bug does not allow to safely use this method: in returned result, one element is missing.
Test case: dynamically create 1000 same custom tags
<customtag><A name="same4all">aa</a></customtag>
the getElementsByName gave 1000 as expected, document.getElementsByTagName and document.all.tags returns 999 elements.
testcase:
http://simulationlabs.com/test/NavigationTest.html
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[jsudds.msft] Thanks for the report. I'll make sure the product team knows about it. Fortunately, this behavior is limited to custom tags only; getElementsByTagName works as expected for built-in elements such as the A tag.