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1 null
Pertaining to a value that indicates missing or unknown data. -
2 null pointer
"A pointer to nothing: usually a standardized memory address, such as 0. A null pointer usually marks the last of a linear sequence of pointers or indicates that a data search operation has come up empty." -
3 Variant data type
"The default data type for variables that don't have type-declaration characters when a Deftype statement isn't in effect. A Variant can store numeric, string, date/time, Null, or Empty data." -
4 Yes/No data type
"A field data type you use for fields that will contain only one of two values, such as Yes or No and True or False. Null values are not allowed."نوع بيانات نعم/لا -
5 ObjectLink
"An OLE data format that describes a linked object, identifying the class, document name, and name of an object. Each of these data items is a null-terminated string." -
6 variant expression
"Any expression that can evaluate to numeric, string, or date data, as well as the special values Empty and Null."
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