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Copyright (C) 2004 James Lowe, Jr.
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SWPACKAGE OUTPUT FORMAT
</TITLE>
<PARA>
The output format is either one of two formats specified in POSIX.1 (ISO/IEC 9945-1)
which are tar (header magic=ustar) or cpio (header magic=070707).  
The default format of the swbis implementation is "ustar".
The POSIX spec under specifies definitions for some of the ustar header fields.
The personality of the default swbis ustar format mimics GNU tar 1.15.1 and is designed
to be compliant to POSIX.1.
The personality of the "ustar0" format mimics, for pathnames less than
99 octets,  GNU tar 1.13.25 using the "-b1 --posix" options.
This bit-for-bit sameness does not exist for pathnames greater than 99 chars as swbis
follows the POSIX spec and GNU tar 1.13.25 does not.  The "ustar0" ustar personality is
deprecated.  It is only slightly different from 'ustar' in how device number fields are
filled (with spaces, zeros or NULs) for non-device files.
</PARA>
<PARA>
In addition the swbis implementation
supports several other tar variants including bit-for-bit mimicry of GNU tar (1.13.25) default
format which uses a non-standard name split and file type (type 'L').  This format is known as '--format=oldgnu'.
Also supported is the gnu format of GNU tar 1.15.1 specified by '--format=gnu'
</PARA>
<PARA>
The defacto cpio formats are also supported.
"new ASCII" (sometimes called SVR4 cpio) and "crc" cpio formats with header magic "070701" and "070702"
respectively.
</PARA>
<PARA>
Support for "pax Interchange Format" (Extended header tar) described in IEEE 1003.1-2001
under the "pax" manual page is planned.
</PARA>
<PARA>
The entirety of the output byte stream is a single valid file of one the formats mentioned above.
</PARA>
<PARA>
The swbis implementation writes its output to stdout.  The default output block size is 10240 bytes.
The last block is not padded and therefore the last write(2) may be a short write.
The selected block size does not affect the output file contents.
</PARA>
<PARA>
The swbis implementation is biased, in terms of capability and default settings, to the tar format.
Package signing is only supported in tar format.
</PARA>
