|  | The answer to my question is in the FAQ of course.
..Dan
E2M5: COMMAND CENTER:
# The room where the first door leads to has two secret rooms in the space
  between the room and the stairs.  The doors <0xfb80ba93,0x7dbd7cc>
  <0xf8373cba,0x7e031f5> are facing the south and will open automatically to
  reveal Imps and ammo.
+ The ridges <0xfca60096,0x3febfc5> <0xf71000d0,0x3e622b8> of the green lakes
  of the big room south of the begin both lead back to normal territory.
# In the SW is a roughly (--) shaped room.  In the room NW of the middle
  of this (--) is a switch <0xf3efdd28,0x1367f57> which activates a stair so
  you can walk through the fake fire <0xf29412f7,0x18d236d> in the NW corner.
  The teleporter there takes you to an area infested with lost souls.  The west
  wall <0xf4690f4,0x496136d> with the head leads to another room with
  transporter.  That transporter takes you to the switch <0xfe9fb836,0x92ff44b>
  for the secret level.
# In the room east to the room in the south middle with the room to the N,E,
  and W and a view to the circular stairway in the south, is a secret door
  <0xfbaff1cb,0xae3ad8> in the NE corner (near the cozy head-fire) hiding the
  chainsaw.
# In the center of the circular stairway is a anti-radiation suit guarded by
  a demon.  The door <0xf94949db,0xfe6d93d0> to it will open as soon as
  you are at the top of the stairs <0xfa165eed,0xfdd56896>.
# The south door directly after the circular stairway leads to two corridors.
  The eastbound corridor is the way to the exit, the westbound leads to C
  formed green lake in the west.  In the north of that lake is a door
  <0xf1a21e52,0xfe94f08f> (behind the ammo clip).  Follow it to a baron of hell
  in a cage.  North of that you will see a long corridor with three doors to
  the east.  The northern and southern doors lead to a ledge around the lake
  to the east.  The middle door <0xf27dc571,0x826c8a6> (the wall part with the
  pentagram over the ugly head) leads to the isle <0xf5420514,0x823f2c1> in
  the middle of the lake, where you'll find a plasma gun. To activate the
  bridge to the isle, you have to push the button <0xf2aff9f7,0xfd1cd93e> in
  the room in the center of the C-formed lake you passed while coming here.
  BTW: If you fall in the lake, the transporter <0xf42dc0b0,0x7500bcf> in the
  indention in the SW brings you back to the beginning.
# In the slime lake mentioned above, not only is there a teleporter,
  but there is also another niche with a cell pack in it
  <0xf29859a4,0x8bf7c8b>.
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