A has an associated lower bound (null or a key).

A has an associated upper bound (null or a key).

A has an associated lower open flag. Unless otherwise stated it is unset.

A key range has an associated upper open flag. Unless otherwise stated it is unset.

A may have a lower bound its upper bound. A must not have a lower bound its upper bound.

A containing only key has both lower bound and equal to key.

• The lower bound is null, or it is key, or it is both equal to key and the is unset.

• The upper bound is null, or it is key, or it is both equal to key and the is unset.

• If the lower open flag of a is unset, the lower bound of the key range is included in the range itself.

• If the of a key range is unset, the key of the is included in the range itself.

• If the upper open flag of a is set, the upper bound of the key range is excluded from the range itself.

The steps to convert a value to a key range with value and optional null disallowed flag are as follows:

1. If value is a , return value.

2. Let key be the result of running the steps to convert a value to a key with value. Rethrow any exceptions.

3. If key is invalid, a ““ .

4. Return a key range key.