Loading tables into TOPCAT is done either from the command line
when you start the program up or
using the Load Table dialogue.
For FITS and VOTable formats
the file format can be detected automatically
(note this is done by looking at the file content, it has nothing
to do with filename extensions).
For other formats though, for instance ASCII or Comma-Separated Values,
you will have to specify the format that the file is in.
In the Load Window, there is a selection box from which you can
choose the format, and from the command line you use the
-f flag - see Section 10 for details.
You can always specify the format rather than using automatic detection
if you prefer - this can be a good idea if a table appears to
be failing to load in a surprising way, since it may give you
a more detailed error message.
In either case, table locations may be given as filenames or as URLs, and any data compression (gzip, unix compress and bzip2) will be automatically detected and dealt with - see Section 4.2.
Note: in some earlier versions of TOPCAT, ASCII
format tables could be detected automatically, so you could load
them by typing something like "topcat table.txt".
In the current version, you have to signal that this is an
ASCII table, for instance by typing "topcat -f ascii table.txt".
The following sections describe the table formats which TOPCAT can read.