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Atoms
User Guide > How to Work with... > OCR > Technical Specifications > Regular Expressions > Anatomy of a Regular Expression > Atoms

The smallest building block of a regular expression is an atom that corresponds directly to one character in the target field. An atom can be one of the following:

Though a portion of a regular expression enclosed within parentheses '( )' can correspond to more than one character in the target field, syntactically we treat it as an atom, so that all operations that can be applied to atoms can also be used with parenthesized regular expressions. See an example for this in the Multipliers topic.