View source for RED (Knowledge Dynamics)

{{FormatInfo
|formattype=electronic
|subcat=Archiving
|extensions={{ext|red}}, {{ext|lif}}, {{ext|001}}, ..., others
}}
'''.RED''' is an installer-archive format, apparently associated with ''INSTALL'' for DOS, and maybe other software from Knowledge Dynamics Corporation (of Canyon Lake, Texas, later San Antonio).

The identifier "RED" is probably derived from "Reduce", which is the name of a software component and a proprietary compression algorithm.

See also [[LIF (Knowledge Dynamics)]], the presumed predecessor format.

== Format details ==
''[This section contains unofficial information based on reverse engineering. It was written for the fileformats.archiveteam.org wiki.]''

A RED archive is a sequence of member file structures, each with the following fields. If a file is split over multiple volumes, each fragment has a header.

{| class="wikitable"
! Offset !! Size !! Description
|-
|0  || 2 || Signature: ASCII "<code>RR</code>"
|-
|2  || 1 || Unknown, always 0x01.
|-
|3  || 1 || Header size, from the start of the <code>RR</code> signature. Always(?) 41. 
|-
|4  || 4 || [[MS-DOS date/time|DOS time, date]]
|-
|8  || 4 || Compressed size (of this fragment, for split files)
|-
|12 || 4 || Decompressed size
|-
|16 || 2 || Probably reserved for CRC of compressed data, but none of the known compression schemes use it.
|-
|18 || 2 || CRC of decompressed data
|-
|20 || 2 || Fragment number, if the file is split over multiple volumes. The first fragment is 1. This field is 0 for files that are not split.
|-
|22 || 2 || "Is last fragment" flag. This field is 1 for files that are not split.
|-
|24 || 2 || Compression scheme. Two schemes are known to exist. 1 is uncompressed. See below for scheme 11.
|-
|26 || 13 || Filename
|-
|39 || 2 || CRC of header, excluding the signature and this field.
|-
|41 || ... || Compressed data
|}

=== Compression ===
Compression scheme 11 compresses the data with [[LHA]]'s "lh5" scheme, then segments it. The compressed data is split into segments of 4094 bytes (fewer for the last segment of each file or fragment), and a two-byte CRC (of the compressed data in the segment) is inserted at the end of each segment.

=== CRC ===
The CRC algorithm is [[CRC-16#CRC-16/IBM-3740|CRC-16/IBM-3740]]. Though RED is mainly a little-endian format, ''some'' of the CRC fields use big-endian byte order.

== Identification ==
RED files apparently start with bytes {{magic|'R' 'R' 0x01 0x29}}.

== Software ==
* Reduce - INSTALL Format Librarian (An interactive DOS utility)
** Reduce v3.20.02: [{{DiscMasterURL|browse/31341/Chip-Special_1996-03_CD-Service-3.bin/miro/pcm10/202711.zip/REDUCE.EXE}}]
** Reduce v3.20.04: [{{DiscMasterURL|browse/43739/Shareware%20cdrom%20prog%2024.iso/DJ42NTA4.ZIP/REDUCE.EXE}}]
** Reduce v3.31: [{{DiscMasterURL|browse/29884/ibm2680-2689/ibm2687.tar/ibm2687/S-MW7101.ZIP/wire71.rar/CDROM/REDUCE.EXE}}]
* {{Deark}}

== Sample files ==
* [http://www.bbsdocumentary.com/software/IBM/DOS/PCBOARD/ BBS Software Directory: PCBOARD] → pcb153-*.zip → ...
* {{DexvertSamples|archive/redArchive}}

== Links ==
* [https://web.archive.org/web/19991110100412/http://www.install.com/install.htm INSTALL website (1999 archive)]