Draft FAQ
Ilana Stern
focuses less on *what* the answers are, than on *where* to get the
answers. Please send me your comments.
When we are happy with this document, it will be regularly posted to
news.answers and sci.answers as well as here. Chris Houck will try to
also make it available as an HTML document in the NCSA archive somewhere.
--------cut here--------
This is a DRAFT FAQ for the sci.data.formats newsgroup. Contents:
-2) How to use this document
-1) How to get a current copy of this document
0) Resources for format information
1) How to use the data retrieval methods
2) Why isn't my favorite format on this list?
Each (major) section has a "Subject:" line, so you can search on the
subject title above to find the section quickly.
This article is copyright (c) 1993 by Ilana Stern. It may be freely
distributed provided that this copyright notice and the information
on retrieving a current copy are not removed.
---------------
Subject: How to use this document
Most FAQ (Frequently Asked Questions) documents list many questions and
their answers. This FAQ is (mostly) devoted to answering only one question:
"Where can I find documentation and software for <X> data format?"
As the amount of information available over the networks has been
increasing, so have the methods by which this information can be obtained.
No longer is direct usage of FTP the only, or even the most frequent, method
of obtaining data; we now have Gopher, Wais, and WWW, as well as many
site-specific interfaces. Because the information itself may be accessible
in many different ways, this FAQ will identify resources in terms of
URLs (Uniform Resource Locators). This will also help us convert this
FAQ to a hypertext document, so that it can be used with a WWW browser
to go directly to any of the listed sources.
Here's a glossary, so you can decode the URLs if necessary to reach
the sites:
ftp://host.name.domain/directory/[subdirectory/[filename]] ftp site
http://host.name.domain/directory/[subdirectory/[filename]] www server
telnet://host.name.domain telnet site
gopher://host.name.domain gopher server
wais://host.name.domain wais server
news:newsgroup.name newsgroup
So, for example, if a document is available at ftp://ncardata.ucar.edu/
it means that you should ftp to ncardata.ucar.edu, and the information is
in the top-level directory.
If you don't know what these information retrieval methods are, see
section 1 of this document.
---------------
Subject: How to get a current copy of this document
[Note: this FAQ hasn't been registered with news.answers yet, so
you can't really get a copy from rtfm.mit.edu yet.]
A current copy of this document can be obtained by anonymous FTP from
ftp://rtfm.mit.edu/pub/usenet/news.answers/data-formats.
If you don't know what FTP is, see section 1 of this document.
If you can't use FTP, send email to mail-...@rtfm.mit.edu with
send /pub/usenet/news.answers/data-formats
as the only text in the message (leave the subject blank).
This document is also archived at [other archival sites]. If
you would like to put this article in an archive and want to receive
a new copy automatically at every update, please send me email.
---------------
Subject: Resources for format information
FITS Flexible Image Transport System (Astronomy)
FITS is the standard data interchange and archival format of the worldwide
astronomy community. Format description and software is available from
ftp://fits.cv.nrao.edu/fits.
Another site with FITS information is ftp://nssdca.gsfc.nasa.gov. The
newsgroup news:sci.astro.fits is devoted to discussion of the FITS format.
If you've searched all these resources and still have questions, you
can direct them to Barry Schlesinger at bschle...@nssdca.gsfc.nasa.gov.
GRIB GRid In Binary (Meteorology)
GRIB is the World Meteorological Organization (WMO) standard for gridded
meteorological data. Unfortunately it is still not very "standard", as
some organizations use their own versions. A format description for WMO
GRIB can be found at ftp://ncardata.ucar.edu/datasets/ds084.5/format_grib,
and read code is in the file access_grib.f in the same directory.
If you need GRIB to read ECMWF data, the above format description, along
with the ECMWF-specific parameter table, and a list of differences between
WMO and ECMWF GRIB, is in ftp://ncardata.ucar.edu/datasets/ds111.2/format.
Read code can be found in ftp://ncardata.ucar.edu/datasets/ds111.2/software.
If all else fails, contact Ilana Stern at il...@ncar.ucar.edu.
HDF Hierarchical Data Format (Various)
HDF is a self-defining file format for transfer of various types of data
between different machines. The HDF library contians interfaces for storing
and retrieving compressed or uncompressed raster images with palettes, and
an interface for storing and retrieving n-Dimensional scientific datasets
together with information about the data, such as labels, units, formats,
and scales for all dimensions.
Source code and documentation are on ftp://ftp.ncsa.uiuc.edu/HDF.
Some general information on HDF, including a FAQ, is available from
http://www.ncsa.uiuc.edu/SDG/Software/HDF/HDFIntro.html.
netCDF Network Common Data Format (Various)
NetCDF is an interface for scientific data access which implements a
machine-independent, self-describing, extendible file format. Source code
and documentation for the netCDF data access library is available from
ftp://unidata.ucar.edu/pub/netcdf or gopher://gopher.unidata.ucar.edu:70.
A FAQ is here also, as well as pointers to other available software packages
which use netCDF data. Questions and answers about netCDF can be searched in
the index wais://wais.unidata.ucar.edu:210/unidata-support-netcdf.src.
A recent paper (Jenter and Signell, 1992) which provides a good introduction
to netCDF is available as ftp://crusty.er.usgs.gov/pub/netcdf.asce.ps.
A mailing list, netcd...@unidata.ucar.edu, exists for discussion of the
netCDF interface, and for announcements of netCDF news: to subscribe, send
a request to netcdfg...@unidata.ucar.edu. The archives of netcdfgroup
are available from ftp:unidata.ucar.edu/mail-archives/netcdfgroup, and also
in the searchable index wais://wais.unidata.ucar.edu:210/netcdf-group.src.
For more information, contact sup...@unidata.ucar.edu.
Miscellaneous graphics formats (Graphics)
These formats for storing graphics files -- TIFF, GIF, JPEG, FLI, CGM,
and so on -- are more properly discussed in news:comp.graphics. A small
amount of documentation on these and other graphics formats is on
ftp://zamenhof.cs.rice.edu/pub/graphics.formats.
---------------
Subject: How to use the data retrieval methods
This section only describes FTP and telnet in any detail; for other
methods, FTP sites are given, so you can get information on them yourself.
1. FTP
2. Telnet
3. Gopher
4. Wais
5. WWW
1. How to use FTP
FTP (File Transfer Protocol) allows transfer of files between two computers
which are on the Internet. To access the FTP areas listed here, at your
system prompt type "ftp" followed by the name or IP number (the number
in brackets next to the system name in the listing below) of the desired
system. For example, to access ncardata.ucar.edu you'd type
ftp ncardata.ucar.edu
or
ftp 128.117.8.111
Use "anonymous" as your login and your email address as the password (if
requested).
[Note: quotes ("like this") are used to set off names of directories and
files, or commands you'd type, and are not part of these names.]
Not all FTP systems accept the same commands, but here's a list of the
most useful:
ls list files in the current directory.
cd change directory, e.g. "cd wx" changes to the wx directory.
binary sets binary mode
ascii sets ascii mode (the default). Use for retrieving text.
get retrieves a file, e.g. "get readme" gets a file called readme.
bye exits FTP.
If you can't seem to connect to the site, check to see if it is a telnet
site. If it is, follow the instructions in the following section instead.
If you can't FTP from your site, use one of the following ftp-by-mail servers:
ftp...@decwrl.dec.com ftp...@src.doc.ic.ac.uk
ftp...@cs.uow.edu.au ftp...@grasp1.univ-lyon1.fr
Send an e-mail message to the closest address, with the lines:
reply your_a...@some.where <- replace with your real email address
connect ncardata.ucar.edu <- for example
cd datasets/ds111.2/software
get access_sun.f
quit
For complete instructions, send a one-line message reading "help" to the
server. Please don't ask me for help!
2. How to use telnet
Type "telnet" followed by the name or IP number of the desired system. These
publicly accessible systems generally allow you to log in but put you in
a restricted shell, from which only a certain menu of commands is available.
The description for the site will include the login to use.
If you can't seem to connect to the site, re-check its description in the
document; if it's an FTP site, follow the instructions in the previous
section instead.
3. Gopher information
Available by ftp at ftp://rtfm.mit.edu/pub/usenet/news.answers/gopher-faq.
4. Wais information
Available by ftp at
ftp://rtfm.mit.edu/pub/usenet/news.answers/wais-faq/getting-started.
5. WWW information
Supposedly also available from rtfm, but so far only available *on* WWW
as far as I can tell.
---------------
Subject: Why isn't my favorite format on this list?
If you don't see a format you're interested in here, it could be one
of three reasons. First of all, there are a lot of formats which are
out of the scope of this newsgroup: it ain't named *sci*.data.formats
for nuthin', you know. Formats used in commercial spreadsheet and
word-processing software aren't scientific data formats, and aren't
discussed in this group.
Second, it may be that nobody has given the FAQ organizer any information
on sources for information on that format. So ask the newsgroup -- and
if you do get a response, please let me know what it is!
Finally, you may ask on the net, and hear nothing, because the
data format description just *isn't* publicly available. For most
scientific data formats, this is a Bad Thing, and most archivists and
scientists *want* to have their format information available. If
you have such information, but don't have resources to make it
available, please ask around and see if you can get it into an FTP
area or other resource. Please don't publicize private or proprietary
formats without the permission of the author, though.
--
/\
\_][ <--NCAR Ilana Stern dod#009 r.b. cliff swallow il...@ncar.ucar.edu
\______________________________________________________________________