any character whatsoever, even a newline, which normally it would not match. Used together, as r""ms, they let the "." match any character whatsoever, while still allowing "^" and "$" to match, respectively missing object, which is the singleton instance of the type Missing. missing is equivalent to NULL in SQL and NA in R, and behaves like them in most situations. 21.1 Propagation of Missing Values missing This follows the well-established rules of three-valued logic which are implemented by e.g. NULL in SQL and NA in R. This abstract definition corresponds to a relatively natural behavior which is best explained

any character whatsoever, even a newline, which normally it would not match. Used together, as r""ms, they let the "." match any character whatsoever, while still allowing "^" and "$" to match, respectively missing object, which is the singleton instance of the type Missing. missing is equivalent to NULL in SQL and NA in R, and behaves like them in most situations. 21.1 Propagation of Missing Values missing This follows the well-established rules of three-valued logic which are implemented by e.g. NULL in SQL and NA in R. This abstract definition corresponds to a relatively natural behavior which is best explained

any character whatsoever, even a newline, which normally it would not match. Used together, as r""ms, they let the "." match any character whatsoever, while still allowing "^" and "$" to match, respectively missing object, which is the singleton instance of the type Missing. missing is equivalent to NULL in SQL and NA in R, and behaves like them in most situations. 21.1 Propagation of Missing Values missing This follows the well-established rules of three-valued logic which are implemented by e.g. NULL in SQL and NA in R. This abstract definition corresponds to a relatively natural behavior which is best explained

any character whatsoever, even a newline, which normally it would not match. Used together, as r""ms, they let the "." match any character whatsoever, while still allowing "^" and "$" to match, respectively missing object, which is the singleton instance of the type Missing. missing is equivalent to NULL in SQL and NA in R, and behaves like them in most situations. 20.1 Propagation of Missing Values missing This follows the well-established rules of three-valued logic which are implemented by e.g. NULL in SQL and NA in R. This abstract definition corresponds to a relatively natural behavior which is best explained

any character whatsoever, even a newline, which normally it would not match. Used together, as r""ms, they let the "." match any character whatsoever, while still allowing "^" and "$" to match, respectively missing object, which is the singleton instance of the type Missing. missing is equivalent to NULL in SQL and NA in R, and behaves like them in most situations. 20.1 Propagation of Missing Values missing This follows the well-established rules of three-valued logic which are implemented by e.g. NULL in SQL and NA in R. This abstract definition corresponds to a relatively natural behavior which is best explained

any character whatsoever, even a newline, which normally it would not match. Used together, as r""ms, they let the "." match any character whatsoever, while still allowing "^" and "$" to match, respectively missing object, which is the singleton instance of the type Missing. missing is equivalent to NULL in SQL and NA in R, and behaves like them in most situations. 21.1 Propagation of Missing Values missing This follows the well-established rules of three-valued logic which are implemented by e.g. NULL in SQL and NA in R. This abstract definition corresponds to a relatively natural behavior which is best explained

any character whatsoever, even a newline, which normally it would not match. Used together, as r""ms, they let the "." match any character whatsoever, while still allowing "^" and "$" to match, respectively missing object, which is the singleton instance of the type Missing. missing is equivalent to NULL in SQL and NA in R, and behaves like them in most situations. 21.1 Propagation of Missing Values missing This follows the well-established rules of three-valued logic which are implemented by e.g. NULL in SQL and NA in R. This abstract definition corresponds to a relatively natural behavior which is best explained

any character whatsoever, even a newline, which normally it would not match. Used together, as r""ms, they let the "." match any character whatsoever, while still allowing "^" and "$" to match, respectively missing object, which is the singleton instance of the type Missing. missing is equivalent to NULL in SQL and NA in R, and behaves like them in most situations. 21.1 Propagation of Missing Values missing This follows the well-established rules of three-valued logic which are implemented by e.g. NULL in SQL and NA in R. This abstract definition corresponds to a relatively natural behavior which is best explained

any character whatsoever, even a newline, which normally it would not match. Used together, as r""ms, they let the "." match any character whatsoever, while still allowing "^" and "$" to match, respectively missing object, which is the singleton instance of the type Missing. missing is equivalent to NULL in SQL and NA in R, and behaves like them in most situations. 21.1 Propagation of Missing Values missing This follows the well-established rules of three-valued logic which are implemented by e.g. NULL in SQL and NA in R. This abstract definition corresponds to a relatively natural behavior which is best explained

any character whatsoever, even a newline, which normally it would not match. Used together, as r""ms, they let the "." match any character whatsoever, while still allowing "^" and "$" to match, respectively missing object, which is the singleton instance of the type Missing. missing is equivalent to NULL in SQL and NA in R, and behaves like them in most situations. 21.1 Propagation of Missing Values missing This follows the well-established rules of three-valued logic which are implemented by e.g. NULL in SQL and NA in R. This abstract definition corresponds to a relatively natural behavior which is best explained