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customized
tags.
It
is
used
to
enable
the
definition,
transmission,
validation,
and
interpretation of data between application and organization.
XML
is
different
to
HTML.
HTML
was
designed
to
display
the
data;
it
focuses
on
how
the
data
looks.
On
the
other
hands,
XML
was
designed
to
describe
the
data;
it
focuses on what the data is. XML is useful for carrying data. It is not designed to do
anything.
XML language is consisted of tags. However, the tags are
not predefined. The
designer must define their tags and rule.
Example of XML:
<note>
<to>Tove</to>
<from>Jani</from>
<heading>Reminder</heading>
<body>Don't forget me this weekend!</body>
</note>
2.3.5 Document Type Definition (DTD)
“A Document Type Definition defines the legal building blocks of an XML document.
It
defines
the
document
structure
with
a
list
of
legal
elements.
A
DTD
can
be
declared
inline in your XML document, or as an external reference.” [16]
DTD describe the
format of the
XML
files. In another
word, DTD acts as a rule
for
the
XML.
With
DTD
different
people
or
machine
can
agree
to
use
a
common
DTD
to
interchanging data. DTD is used to verify that a data received is valid or not.
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