#220 Zip archives created by 7-Zip gets wrong header values

[Anonymous]

When creating Zip archive with level set to 'Ultra' and
compression method set to 'Deflate', opening the
archive in PKZIP shows the method as 'DeflateN' instead
of 'DeflateX'. It may not interfere with archive
extraction, but it misdirects users to think 7-Zip is
making zip archives with lower compression ratios,
which is definitely not the case. 7-Zip should set the
method as 'DeflateX' when maximum deflate setting is
used. In addition, to avoid future confusions, when
Zip archive is created, the compression level settings
in the 'Add to Archive' dialogue should match the PKZIP
convention.

The level settings must show 0-9 in the 'Add to
Archive' dialogue, but the flag stored within the
archive will be set based on the level settings. The
flag settings should be displayed alongside with level
settings (eg: '9-DeflateX'). For Deflate and
Deflate64, the header settings are as follows:

Level 1: DeflateS, Deflate64S
Level 2: DeflateF, Deflate64F
Level 3-8: DeflateN, Deflate64N
Level 9: DeflateX, Deflate64X