XYXY

xyxy is a four-character string formed by repeating the two-character sequence 'xy' once, yielding 'xyxy'. It is commonly used as a simple example in discussions of strings, repetition, and pattern matching.

In computing, 'xyxy' serves as a test input for demonstrations of regular expressions, parsers, and tokenizers. For instance, a pattern that matches two consecutive occurrences of 'xy' would accept 'xyxy' but not other configurations. A typical regex example is ^(?:xy){2}$, which matches exactly 'xyxy'.

From a formal-language perspective, 'xyxy' is the concatenation of two copies of 'xy', i.e., an element of the language {xy}^2. It is not a palindrome, since reversing it yields 'yxyx'.

As a literal string, 'xyxy' may appear in data, identifiers, or examples across documents and tutorials. There is no single canonical meaning for 'xyxy' beyond its role as a repeated pattern, and its interpretation depends on context.

See also: string pattern, repetition, regular expressions, concatenation.