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+# Trail System
+ 
+Note that as of Tremulous 1.1.0 there is no way to trigger a trail system with map entities.
+However, a trail system can be attached to a Particle System with the `childTrailSystem` key.
+ 
+Files matching the pattern `scripts/*.trail` are loaded as trail system description files.
+Each `.trail` file can contain an arbitrary number of discrete trail systems, much like a `.shader` file can house many shaders.
+A trail system is declared by a name followed by curly braces within which the functionality of the trail system is defined. For example:
+ 
+```
+   aShinyNewTrailSystem { } 
+```
+ 
+Inside the particle system declaration are placed up to four trail beams. Beams are identified by the keyword beam and curly braces:
+ 
+```
+   aShinyNewTrailSystem
+   {
+ 
+     beam { }
+ 
+     beam { }
+ 
+     thirdPersonOnly
+   } 
+```
+
+The `thirdPersonOnly` keyword may be used to specify that the trail system is not visible from the first person if it relates to that client.
+
+A trail beam describes the appearance of one element of the trail system:
+ 
+- `shader <shader>` - the shader to use to texture this beam.
+- `segments <number>` - the number of quads that make up the beam.
+- `width <frontWidth> <backWidth>` - the width of the beam at the front and back.
+- `alpha <frontAlpha> <backAlpha>` - the alpha of the beam at the front and back.
+- `color { <fr> <fg> <fb> } { <br> <bg> <bb> }` - the color of the beam at the front and back.
+- `segmentTime <time>` - how long a single segment lasts when the trail is only attached at one end.
+- `fadeOutTime <time>` - how long this beam takes to fade away.
+- `textureType [stretch <frontTC> <backTC>][repeat [front|back] <repeatLength>]` - how to texture the beam. `stretch` causes the texture to be stretched from the front to the back using the specified texture coordinates. `repeat` causes the texture to be repeated over a specified length either from the front or the back.
+- `model <model1> <model2> ... <modelN>` - use one of the specified models as the particle. This cannot be used in conjunction with the shader keyword.
+- `modelAnmation <firstFrame> <numFrames> <loopFrames> <fps>sync` - animation parameters to use when model particles are employed.
+- `realLight` - light particles using the lightgrid instead of fullbright.
+- `jitter <magnitude> <period>` - this specifies a random jitter of the position of each beam node by magnitude every period.
+- `jitterAttachments` - if this is specified the end points of the beam are jittered as well as the intervening nodes.