# Terminology ## **Timeline**
Timelines are where you sequence and composite content (layers), events and actions. LightAct can have several independent timelines. In every timeline you can have one or several: * Tracks * Sections * Layers * Markers ### **Timeline group**
Timeline group is a group of one or more Timelines. It is used to control syncing to external timecode sources and to control playstates of Timelines in that Timeline group. ### **Track**
Each Timeline is divided into several Tracks. On each track you can have one or several layers. ### **Layer**
A *layer* is an entity that exists in a *Timeline* and has a beginning and an end (determined by the **Duration** parameter). A *layer* can perform a variety of functions such as content processing & playback, video/image/image sequence/Notch block reading and playback or just some logic. {% hint style="info" %} **Good to know**: Layers in LightAct are called Layer Templates and you can easily create your own. {% endhint %} ### **Layouts**
Layouts are LightAct's node-based system. You can find them in: * Layers * Mappings (in Canvas Maps and Output Maps windows) * Projectors ### **Variable**
A LightAct variable is a container holding information. The information can be a number (integer or float), color, texture or something else. There are 2 types of variables: * **Layer variables** are available only within one layer * **Global variables** can be accessed anywhere ### Section
Section is part of a timeline. Very often sections also serves as cues. ### **Marker**
A *Timeline marker* indicates a position on a Timeline. ## **Viewport** Serves as the visual preview area where you can see how your compositions and mappings will appear in the real world. ### **Video screen**
A *video screen* is a virtual representation of a physical video screen. ### **Thrower**
A *thrower* is a helper virtual object that facilitates mapping of content onto various viewport objects by taking into account their position in the 3D scene of the viewport. ### **3D model**
A *3D model* is a virtual representation of a physical object. *3D models* are usually imported as an *.fbx* or .*obj* assets. ### **Primitive**
A *primitive* is a simple 3D model of a cube, a plane, a sphere or a cone. ### Null object
A *null object* is an ‘empty’ object that can be used as a container of other objects.
It allows you to group objects and move them together. ### **Marker in Viewport**
A *viewport marker* indicates a 3D position in the *Viewport window*. ## **Other** ### **Canvas** ![](https://3312042618-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2F9sVaJpWJhPbmscipukhh%2Fuploads%2FcAEnjCukIEIipHWzVPm5%2Fimage.png?alt=media\&token=b2ae75e9-a4aa-41f6-a155-35bedadaae20) A *canvas* is an entity that holds one texture. The texture can be of an arbitrary resolution. In most cases, content is rendered on a canvas through the Layers. Content is then rendered to various viewport objects through Canvas maps window. ### **Assets**
Asset is an external resource that LightAct uses in a specific project. Examples include: * images, image sequences or video files, * Notch blocks, or TouchDesigner components, * Audio files, * 3D models or * Unreal Engine projects. ### **Video output**
*Video output* is a virtual representation of a physical output on the system’s GPU. ## **DMX** *DMX* stands for DMX512, which is a communication standard commonly used to control lighting and effects. ### **Art-Net** *Art-Net* is a UDP based protocol used to transmit DMX data over Ethernet. It was developed by Artistic License. ### **sACN** *sACN* is a UDP based protocol used to transmit DMX data over Ethernet. It was developed by ESTA. In many aspects it is comparable with Art-Net. ### **Fixture**
*Fixture* refers to a *DMX light fixture*, i.e. a light fixture controlled by DMX.