search-string
    Specifies the string for which to search.

    If the TPU pattern style is being used the search-string is a
    TPU expression which must evaluate to a TPU pattern (for
    example: "'abc' | 'def'").

 replace-string
    Specifies the string to substitute.

    If the TPU pattern style is being used the replace-string is a
    TPU expression which must evaluate to a TPU string (for
    example: "'ghi'").