From your tape editors:

In order to be able to distribute the SIG tapes using the tree
mechanism, we view it as desirable to try to limit the size of
the combined collection to one reel of tape at 6250 BPI. Since
the amount of material submitted is too large to do this any
other way, we have preferred to use data compression programs
to compress the submissions in places, rather than having to
remove items from the distribution arbitrarily.

The tools used are furnished in the .tools subdirectory of the index
directory for the tape collection (in the Fall '91 case, that
would be [91BVAXLT.TOOLS]). To simplify extraction, a few conventions
are adopted to specify how to decompress:

file.ext_LZW	Compressed with LZCOMP, decompress with LZDCMP

file.ext_Z
  or
file.ext-Z	Decompress with COMPRESS -D (in the second case,
			rename to file.ext_z). Note that compress
			deletes the compressed input file if it
			succeeds, so copy if you want the original
			compressed file also.
file.ext-gz (or some file.ext-z) - Decompress with GUNZIP (gunzip file
			to decompress.)
file.TAZ	Decompress with COMPRESS -D as above after rename to
			file.tar_z; then use a tar format reader to
			pull the tar file apart. (Tarread23a will do
			nicely. So will VMSTAR.)
file.TAR_LZW	Handle exactly as file.taz. These files have generally
			been produced on unix systems and the most
			compatible decompressor is Gnu COMPRESS here.

file.ZOO	Decompress with ZOO. Zoo will be used as the default
			compress/decompress utility because it allows
			decompression of selected items in a ZOO archive
			and directories of the archive without decompressing
			first.
file.LZH	Decompress with LHARC. LHARC compresses better than ZOO
			and so is used in some places instead of ZOO.
			lharc l file.lzh gives a directory of the file,
			while lharc e file.lzh pulls the files out of a
			lharc archive.
file.ZIP	Decompress with UNZIP. ZIP compresses comparably with
			ZOO's high-efficiency mode or LHARC, but saves
			VMS file attributes so is the preferred utility
			as of Fall 1992 (first tape after the ZIP
			that preserves VMS attributes was introduced).

file.bck_mmmmm_Z Compressed with COMPRESS, decompress with Compress -d.
			Files named like this are Backup savesets with
			block size mmmmm. Thus if one encounters
			Emacs.bck_4096_Z, one must do the following:
	$ compress -d Emacs.bck_4096
	$ file/record=4096/type=fixed/attr=noimpliedcc Emacs.bck_4096
	  Emacs.bck_4096 is now a valid Backup saveset and can be
	pulled apart with VMS Backup. This is done because LZCOMP
	file attribute encoding changes in VMS 5.4 so that files
	compressed with LZCOMP unde VMS 5.4 cannot be decompressed
	under VMS 5.3 and earlier without attributes getting messed
	up at least. The Compress code is robust and portable and
	not subject to these problems, so this solution will allow
	us to compress savesets in a way which can be used across
	platforms and OSs.

Because some files are compressed for use on other systems with ZOO or
LHARC, these will be named file.zoo_something or file.lzh_something.
These are .zoo or .lzh files but normally will be used on other
systems and will be left compressed generally. Ditto file.zip_something.

Note that some files are compressed as received; these are not touched
by the tapecopy people. Thus, a file *.bck_z or *.bck_lz or so on
may be compressed by either compress or lzcomp. Sometimes custom
tools are used; the files in the [.news60] directory on the 91A
tapes for example need to be decompressed with the DECOMPRESS.EXE
in the directory with the compressed files. The VMSnet archives
files are mainly compressed with LZCOMP and must be decompressed
with LZDCMP. The LZDCMP tool (as well as many others) is included
in the [.tools] subdirectory of this index area.

The tapecopy process this time has used only three compress tools,
ZIP, ZOO and COMPRESS, since the new high-efficiency mode of ZOO is at least
as good as LHARC. The DECOMPRESS_ALL.COM file nevertheless will do
decompression on some of the LZCOMP - compressed files. It will not
however erase the originals of these files; nor will it erase ZOO files.
It is possible some ZOO files intended for non-VMS systems may have
slipped by. If one of these does not decompress correctly try using the
command "FILE/TYPE=LFSTREAM FILE.ZOO" command on it. These files should
have the carriage control attribute reset prior to trying to transfer
them to other systems.

Note: ZOO files destined for VMS systems will be set to stream_lf
here so VMS ZOO will decompose them properly. ZOO files for programs
for other machines will generally be set to fixed 512 byte records for
simpler file transfer. The FILE utility (on these tapes) can be used
to convert these. Generally .ZOO or .LZH files for VMS will be in
stream_lf form, and .ZOO or .LZH files not in stream_lf form are
for some other platform. We will attempt to rename all such to
.ZOO_something or .LZH_something, but a few may slip by.

	Future Help:

When submitting material, please avoid redundant files. Compress your
libraries (especially with /DATA=REDUCE), omit listing or map files,
compile without debug unless you MUST have DEBUG there for some reason.
Don't bother submitting object files if macro source is supplied,
or Runoff output where the input is supplied, as examples. Also, submit
programs only when they've changed since you last submitted them. Repetition
of old stuff does none of us much good. Versions of someone else's old
stuff that you fixed and/or made less crufty are most welcome though.

   If you can supply ONE file named AAAREADME.TXT in the top level of
the directory tree you use (others named something else) it will speed
the tape creation process. Finally, PLEASE try not to use directory
trees deeper than about 4 levels. Deeper trees cause errors during
mastering (where some extra levels are introduced to keep submissions
straight as a step in mastering) and can make reproduction of the final
tape harder. If you can exclude extra directory levels from your
submission, this will be helpful.

Thank you.

Glenn C. Everhart
VAX SIG tapecopy coordinator


Note: The file DECOMPRESS_ALL.COM is a template which can be
used (AFTER edit please) to decompress the saved material on
the distribution. It is located in this directory.
  The decompress_all.com file deletes files as they are
decompressed. Be sure you have a copy of the material before
using this, in case anything has errors.
