http://fileformats.archiveteam.org/index.php?action=history&feed=atom&title=PACKIT_by_MJPPACKIT by MJP - Revision history2026-04-22T18:33:53ZRevision history for this page on the wikiMediaWiki 1.19.2http://fileformats.archiveteam.org/index.php?title=PACKIT_by_MJP&diff=51694&oldid=prevJsummers: Created page with "{{FormatInfo |formattype=electronic |subcat=Archiving |extensions={{ext|ins}}, {{ext|dat}} |released=≤1994 }} :''Not to be confused with PackIt.'' '''PACKIT by MJP''' i..."2026-04-21T13:56:49Z<p>Created page with "{{FormatInfo |formattype=electronic |subcat=Archiving |extensions={{ext|ins}}, {{ext|dat}} |released=≤1994 }} :''Not to be confused with <a href="/wiki/PackIt" title="PackIt">PackIt</a>.'' '''PACKIT by MJP''' i..."</p>
<p><b>New page</b></p><div>{{FormatInfo<br />
|formattype=electronic<br />
|subcat=Archiving<br />
|extensions={{ext|ins}}, {{ext|dat}}<br />
|released=≤1994<br />
}}<br />
:''Not to be confused with [[PackIt]].''<br />
<br />
'''PACKIT by MJP''' is the signature of an installer-archive format, used by:<br />
* Offline Mail Executive (OMX), by SysTech Computer Services<br />
* The Blue Wave Offline Mail Reader, by Cutting Edge Computing<br />
<br />
Archives appear to be uncompressed, though it's possible that the format supports compression.<br />
<br />
== Discussion ==<br />
This format is rare, but documented here in part to distinguish it from similar formats.<br />
<br />
The original author of OMX is Martin J. Pollard, more than likely the "MJP" in the signature.<br />
<br />
In some archives, one of the member files (WELCOME!.000) is a [[ZIP]] file. This causes some unzip software to misleadingly behave as if the whole archive were this one member file.<br />
<br />
== Format details ==<br />
''[Unconfirmed information. Written for the fileformats.archiveteam.org wiki.]''<br />
<br />
Format of an archive:<br />
* 16-byte signature<br />
* Sequence of member files<br />
* 2-byte trailer: <code>ff ff</code><br />
<br />
Format of a member file:<br />
* Two unknown bytes, observed to be <code>ff 00</code>.<br />
* Two fields each containing the file size<br />
* Timestamp<br />
* [[CRC-32#CRC-32/JAMCRC|CRC-32/JAMCRC]]<br />
* Filename size<br />
* Filename<br />
* Unknown byte, observed to be <code>00</code>.<br />
* File contents<br />
<br />
== Identification ==<br />
Files start with ASCII "{{magic|PACKIT by MJP}}", then bytes {{magic|0d 0a 1a}}.<br />
<br />
== Sample files ==<br />
* {{CdTextfiles|simtel/stmsdos9709/disk1/DISC1/MAILNEWS/OMX100.ZIP|OMX100.ZIP}} → INSTALL.DAT<br />
* {{CdTextfiles|simtel/stmsdos9709/disk1/DISC1/MAILNEWS/BW23_DOS.ZIP|BW23_DOS.ZIP}} → BWAVEDOS.INS<br />
* {{DexvertSamples|archive/packItInstallationArchive}}</div>Jsummers