http://download.java.net/jdk6/docs/api/java/text/Collator.html

states that

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in Czech, "e" and "f" are considered primary differences, while "e" and "ê" are secondary differences, "e" and "E" are tertiary differences and "e" and "e" are identical
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In fact Czech does not use the "ê" character (U+00EA). The author was probably thinking of E with hacek, U+011B, which Bugster stupidly refuses to let me type here.