In conventional database terminology, records and fields are equivalent to items and attributes. However, the terms records and fields do not fully convey the structure of items in the mvBase system.
Each item is a variable-length string of characters. The structure of an item is defined by the presence of delimiters, special characters that indicate structural elements. The mvBase system delimiters are shown in the table below. An item is a sequence of variable-length attributes. An attribute corresponds to a line when the item is listed vertically (such as in the Editor). Attributes can contain any number of values. If an attribute contains more than one value it is said to be MultiValued. Values, in turn, can be further divided into any number of subvalues.
|
Mark |
Representation |
ASCII Value |
|
Attribute |
^ |
254 |
|
Value |
] |
253 |
|
Subvalue |
\ |
252 |
Using these structures, a database file could be structured such that each item was the equivalent of a collection of records and each attribute was the equivalent of a collection of fields. The value mark delimits the contents of each field within the attribute and the subvalue mark delimits multiple entries in a single field.
The following topics are presented in this section:
Controlling and Dependent Specifications
See Also