The new DRF format is considerably more useful than the old one. It has the
following advantages:
  Version number
  Small size
  Records sound as well as graphics
  Text rather than binary format
Rather than encoding each graphics operation (the output data) it encodes the
input data (keystrokes, level data, random seeds)

The file is layed out as follows. No quote (") characters appear in a DRF file,
they serve to indicate data in the file. No line of a DRF file should ever be
more than 79 characters.

First comes the header:

The first line is "DRF" - indicates this is a DRF file
The second line is the version of Digger it was created with, e.g.
 "AJ DOS 19981013"
 This has several parts:
  Initials of person who compiled this version.
  (space - separator)
  Platform (only DOS exists at the moment).
  (space - separator)
  Compilation date in yyyymmdd format (Y2K compatible, easy to compare).
The third line is the mode. Currently supported modes are:
 "1" - One player
 "2" - Two players
 "M2" - Two player simultaneous
 "Gx" - Gauntlet mode for x seconds
 "M2Gx" - Two player simultaneous gauntlet
 There may also be a "U" (for Unlimited lives) and an "Ix" (start on level x).
The fourth line is the bonus score in decimal.
The next 80 lines (5-84 inclusive) are the level data (15 characters per line,
15 horizontal cells per screen, 8 screens of 10 vertical cells).

The next lines describe the actual game. They are in blocks. A block contains
1 round (a round finishes when you complete a level, die or exit). Each block
is in 3 parts:
 First line: random number seed: 8 digit hex number
 Following lines: RLE encoded game data. Letters (udlr) denote directions, s
  is stopped. Capital letter is used if Digger is firing. A number n following
  indicates this is state is repeated n times. One letter is used per frame of
  action, and the default speed is roughly 15 frames per second.
 Last line: "EOL" - This is required to tell the playing subroutine if the
  game finished prematurely (by pressing F10) otherwise it would just go on
  looking for keystrokes.

The game knows how many blocks there should be. It depends on the mode and the
player's score (since there is an extra block for each extra life).

After the blocks comes the line "EOG". This signals that this is the end of
the game, and is needed if the player pressed F10 during the death march.

Finally, if the player got a high score, his/her initials form the last line
of the file. This is not currently used in playback, but helps to automate the
addition of DRFs to the high score table on the website.

The new DRF format does not record multiple games, the title screen or the
"Enter Your Initials" screen - this would be difficult and fairly pointless.
Also (as with the original), pauses are not recorded.
