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LEGEND.TXT Key to Linedef Reference V3 by Jim Flynn 
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cf. LNDFBYFN.TXT for linedef quick reference sorted by function
cf. LNDFBYNO.TXT for linedef quick reference sorted by number
cf. DOOMREFR.TXT for all this info and more in one document.
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LEGEND
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 Abbreviations
   n. = neighbor
   min = minimum
   max = maximum
   inc = inclusive
   exc = exclusive

 A * appears on the left of any description line that only works for
 DOOM 1.666 engine and above.

 Linedef Description Headers:
 ----------------------------

 Example:
  #    u1  u2 Trig Brief description       Qualifier    Speed Sound
  59    5   7 W1&  Absolute rise 24        T:SEC,DMG    slow  (mover)

 #
  is the linedef function type number 0-143

 u1 and u2 
  are the number of occurrences of a trigger in Doom 1 and 2.

 Trig 
  represents the conditions that cause the function to be activated.

  The trigger symbol may start with "n" if the function does not
  require a sector tag to operate.

  The basic trigger symbol letters are as follows:
 
     S = switch/door, 1st sidedef must be used with spacebar to activate
     W = walkover, only teleport linedefs req. approach from 1st sidedef
     M = monster walkover, activated only by monster walking over line
     G = impact trigger, activated on hit: fists,chain,bullet,shell
     - = no trigger required like animated wall

  The next letter in the trigger symbol is the repeatability of the
  function, "1" for once only (per linedef), and "R" for repeatable.
  This may be - if the repeatability does not apply as for end level.

  The final letter in the trigger symbol can be "m" or "&". The "m"
  indicates that a monster can activate the function. The & indicates
  that once activated, all other functions on the sector are locked out
  even after the "&" function is completed.

 Brief description

  This column attempts to state in English what the function does.

 Qualifer
  
  Which key is required, crusher attribute, texture changes

 Speed

  Rough relative up/down velocity involved in the operation

 Sound

  Name of the sound associated with the action

 Texture Change Descriptions
 ---------------------------

  Texture changes involve copying attributes from another sector to
  the one that is changing. If the sector being copied is based on
  the line triggering the change the description is prefaced with
  "T:" to indicate a trigger model change. This means that the sector
  on the first sidedef of the triggering linedef is the one copied in
  the change. If the sector being copied is based on the sector being
  changed then it is the sector that is on the other side of the
  lowest numbered two-sided linedef in the changing sector. Such a
  change is prefaced with "N:", for a numeric model change.

  The remainder of the texture change description lists the attributes
  copied. "0" means that the changing sector type is set to 0 and only
  the floor texture is copied. "SEC" means that the secret attribute of
  the model sector is copied. "DMG" means that the damage attribute of
  the model sector is copied. Floor textures are ALWAYS copied, Ceiling
  textures, lighting attributes and heights are NEVER copied.

 Floor motion directions
 -----------------------

  Floor linedefs described as "Down to" functions will move the floor
  at the speed indicated if the target height is lower. The height
  change is instantaneous if motion is in other direction. Floor
  linedefs described as "Up to" act in a similar fashion but in the
  opposite direction.

 Door functions
 --------------

  A door function described using commas only works when the door
  is stable in the opposite state to the function. A door function
  described using slashes will work anytime to toggle the
  opening/closing state of the door.
    
