Database and Expert System Technology - Information Systems Reengineering, Integration and Normalization - page 64

• Impropernesting
Sub-element
Sub-element is an element inside another element.
<account> <balance> …. </balance> </account>
<balance>…</balance> is a sub-element of <account>…</account>
Attribute
An element may have several attributes, but each attribute name can only occur
once.
<account type = “checking” charge = “5”>
Name Space
XML data is to be exchanged and appended by regions.
Same tags may be used by multiple regions.
• Cannotavoidusingthesamenames
Solution: “name_space: element_name”
Complex Element
A complex element is an XML element that contains other elements and/or attri-
butes.
There are four kinds of complex elements:
• Emptyelements
• Elementsthatcontainonlyotherelements
• Elementsthatcontainonlytext
• Elementsthatcontainbothotherelementsandtext
Element Groups
Element groups are defined with the group declaration, like this:
[VJURXSQDPH ³SHUVRQJURXS´!
[VVHTXHQFH!
[VHOHPHQWQDPH ³ILUVWQDPH´W\SH ³[VVWULQJ´!
[VHOHPHQWQDPH ³ODVWQDPH´W\SH ³[VVWULQJ´!
[VHOHPHQWQDPH ³ELUWKGD\´W\SH ³[VGDWH´!
[VVHTXHQFH!