||Is it impossible to use
characters not in the character set?
||It is possible to use them,
but there are several problems involved.
PCs usually possess a
user-defined character function.
This function allows the user to record
particular characters that they want to use, and
handle them just as if they were registered as
These are called user-defined characters.
This is a very convenient function, and allows
you to use characters that do not have a
character code by recording those you wish to
use, thus making it possible to use any character
However, user-defined characters currently have
the following problems.
number of characters available may be too few.
For example, the standard
number of user-defined characters available under
Windows is 1880 characters. However, this may be
insufficient when recording information such as
large numbers of individuals' names.
transfer is impossible.
are basically meant to be recorded on one PC, and
can only be used on that PC. However, these days
it is normal for PCs to be connected together via
LANs, the Internet and other data communication
methods. If a document using user-defined
characters is transferred over a network, the
necessary characters are not recorded on the PC
on the receiving end, resulting in those
characters not being displayed. For this reason,
it is considered good manners not to use
user-defined characters when sending electronic
mail or other digital information.
Of course, even if the data is transferred
between PCs by floppy disk, the same phenomenon
There are two ways of dealing with these
One is to make a character set that includes more
characters and use that instead. At the moment,
new JIS standards - the third and fourth JIS
standards and JIS X 0213 - are in the process of
being defined, but they have not yet reached a
The other way is to create a safer process for
handling user-defined characters. This includes
XKP (Windows NT eXtended Kanji Processing).