Update information file is a text file that contains sectons for
different program versions. Each section begins with version number in
square brackets.

[424]
+drwebase.vdb, 1234DEFA
=changed.vdb,
-deleted.vdb,

[425]
=drweb32.dll, 0C8743FE
-deleted2.dll,

After the line with version number up to beginning of the next section
there are lines with complete set of files that belongs to the indicated
version. Format of the line with file description is the following:

     <id><filename>,[<crc32>]

    <id> can be one of the symbols '+', '=' or '-'. The symbol '+ ' means
that the indicated file was added to file set, symbol '=' means that
file was changed, symbol '-' means that indicated file must be exluded from
set. Program ditectory can be cleared of old files (for example, old
add-ons) using symbol '-'. <filename> describes file name included in
version. After comma that follows file name the CRC32 of file in hexadecimal
format is indicated optionally.

    There is a special section type, a separator that looks like this:

[---]

    This section type separates version groops. Accumulation of information
of updated files begins from section with number of necessary version and
is stopped by this section-separator. The next sections are missed.

Update description file (drweb32.lst) you can fetch from:
http://update.drweb.com/unix/drweb32.lst

But you must add two HTTP headers:
X-DrWeb-KeyNumber: user number (a value of Number parameter from the [User]
  section of the key file)
X-DrWeb-Validate: md5 summa of a key file

Example of request (using wget):
# wget --header="X-DrWeb-Validate: 01234567890123456789012345678901"\
       --header="X-DrWeb-KeyNumber: 1234567890"\
       http://update.drweb.com/unix/drweb32.lst
