This Theos port supports all the unusual features of Theos filesystem.

Under Theos filesystem files are typed. Types include :
- stream
- relative
- keyed
- indexed (ISAM)
- program (86 real mode, 16 bits protected mode, 32 bits protected mode)
- directory
- library (contains files of any other types librry and directory excepted).

Most of the information on the type and on the structure of a file are not
contained in the file itself but its in directory entry. For all types of
files, directory and stream files excepted, this information is vital. If it
is lost, the file can no longer be usable.

In zip files the information is stored in an extra block with type "Th".

A few years ago I ported ZIP for internal use and spreaded it a little around
me. It was using a non portable extra block structure. Its type was "TH".
For backward compatibility it is supported by UNZIP 5.4.0 port to Theos.
ZIP archives created with ZIP 2.3 port MUST be unzipped with 5.4.0 or a later
version.

Also disk search sequence is supported. The disk name is not stored into
the zip archive.

Thanks to Bob Baker from Stockboy Services who spent his time to check this
port under other conditions than mines.

Jean-Michel Dubois
IBC France / THEOS France
jmdubois@ibcfrance.fr
jean-michel-dubois@wanadoo.fr