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# If the filename contains characters not allowed in an 8. 3 name ( including space which was disallowed by convention though not by the APIs ) or either part is too long, the name is stripped of invalid characters such as spaces and extra periods.

Other characters such as "+" are changed to the underscore " _ ", and uppercased.

The stripped name is then truncated to the first 6 letters of its basename, followed by a tilde, followed by a single digit, followed by a period "< tt >.</ tt >", followed by the first 3 characters of the extension.