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Components of the Sym application
The three main components of the Sym application are the content, the tools used to edit and manage the content and the libraries that provide the objects and functionality that are used to create and edit expressions.
Dialogs
The Rendering Editor
Renderings control how each object is displayed in a document. Renderings are created and edited using the Rendering Editor and are attached to object definitions in Object Modules. An object definition can contain zero, one or more renderings. If no rendering is assigned to an object definition, a default rendering is used to display the object.
Working with Parameters
The number of parameters a rendering can contain is defined by the object’s type definition. For example, if the type definition is Type:: Real → Real → Real, then a rendering for that object can have at most two parameters. You can create renderings that have fewer parameters than the maximum set by the type definition.

Components of the Sym application
The three main components of the Sym application are the content, the tools used to edit and manage the content and the libraries that provide the objects and functionality that are used to create and edit expressions.
- Content
  Content windows include Document Modules, Object Modules and Unit Test Modules. With the exception of the Properties windows which are attached to modules, all of the windows in the Sym application can be dragged and docked in a variety of locations to provide a way to customize the layout of the main application window.
- Tools
  In addition to the content of the application there are several tools available to assist you in creating and managing the content of a document, like the Document Explorer, Object Browser and Unit Test Runner.
- Libraries
  There are a number of libraries that are available online that can be used with Sym documents.
- Dialogs
  - The Rendering Editor
    Renderings control how each object is displayed in a document. Renderings are created and edited using the Rendering Editor and are attached to object definitions in Object Modules. An object definition can contain zero, one or more renderings. If no rendering is assigned to an object definition, a default rendering is used to display the object.
    - Creating a New Rendering
      If you are creating new objects, you will often create a rendering for those objects. The Rendering Editor provides a tool for creating a new rendering.
    - Navigating the Rendering Editor
      The rendering editor has three main areas, each of which is used for different editing actions.
    - Connecting and Positioning the Parts of a Rendering
      The components of a rendering contain connections that define the position of each component relative to one of the other components of the rendering. There is always one component of a rending that serves as the starting point for laying out the positioning of all of the other compoents.
    - Working with Parameters
      The number of parameters a rendering can contain is defined by the object’s type definition. For example, if the type definition is Type:: Real → Real → Real, then a rendering for that object can have at most two parameters. You can create renderings that have fewer parameters than the maximum set by the type definition.
    - Working with Symbols
      A symbol is a fixed character or string, such as the + and - used in a + b and a - b objects. An object rendering can contain an unlimited number of lines and symbols. Symbols are added and edited using the Symbol Editor. Symbols are used purely for display and have no impact on the functionality of an object.
    - Working with Lines
      Lines of any length and direction are added to a rendering by drawing them with the mouse. Lines are used purely for display and have no impact on the functionality of an object.
    - Working with Groups
      Creating a group in a rendering allows you to treat multiple components of the rendering as a single entity for purposes of positioning and scaling. As an example, if a rendering contains parentheses and there are multiple components of the rendering inside of the parentheses, the components inside the parentheses can be put in a group so that the parentheses can be set to scale to the size of the group. There are some renderings where creating a group is necessary to get the rendering to display in the desired manner.
    - Scaling Symbols and Lines
      While some symbols will always stay the same size, the ‘+’ sign for example, others need to scale to the size of the equation. The division line, parentheses, and the square root object are examples. The scaling described here can only be applied to symbols and lines. Parameters can be scaled by setting the Scale property in the Rendering editor, but can't be scaled to other parameters the way that symbols and lines can.
    - Understanding the Centerline
      There are expressions where the connections between the components of the rendering needs to be placed in a location other than just the top, middle or bottom of the box containing a component. The centerline is used to define another connection point for a component in a rendering that is used for these cases.
    - Creating Renderings for List Objects
      An the object with a type definition of the form TypeA[] -> TypeB is referred to as a "list object". Instances of list objects can have any number of parameters. In the Rendering Editor, you can create renderings with zero parameters, one parameter, or you can create a list rendering that defines how the object is rendered when an instance of the object has more than one parameter.
  - The Options Dialog
    The Options dialog is used for settings that are independent of the document that is currently loaded. The settings include the document location, the export location and whether or not type errors are fixed automatically.
  - The Document Options Dialog
    The Document Options dialog is used for settings that are part of each document. The settings include the Copy Exporter and the Notation. The Document Options dialog is opened by selecting Edit > Document options... from the main menu.

Working with Parameters

The number of parameters a rendering can contain is defined by the object’s type definition. For example, if the type definition is Type:: Real → Real → Real, then a rendering for that object can have at most two parameters. You can create renderings that have fewer parameters than the maximum set by the type definition.

To delete a parameter, highlight the parameter in the design area and press the delete button. Only the last parameter in the rendering can be deleted.

If the rendering has fewer than the maximum number of parameters, you can add a parameter by clicking the Add parameter button or right-click the name of the object in the rendering tree and select Add parameter from the context menu.

If the rendering has the maximum number of parameters, the Add parameter button and context menu item are disabled.

If the object is a list object (an object with a type definition of the form [TypeA] -> TypeB), then the handling of the number of parameters in the rendering Editor is different. See Creating Renderings for List Objects for more information.

Right click on a parameter within the rendering tree or in the design box to access the following options:

Add copy: Adds a copy of the selected parameter to the bottom of the tree and appends it to the far right side of the rendering. Note that this doesn't add another parameter, it just allows you to put another copy of this same parameter into the rendering. This is not commonly needed but is useful, for example, in expressions like:
where we always want the parameter that represents the order to be the same in the numerator and denominator.
Add symbol: Adds a new symbol to the bottom of the tree and appends it to the far right side of the rendering. The Edit Symbol dialog box is used to construct the symbol. For more information, see Working with Symbols.
Add line: Adds a new line element to the bottom of the rendering tree and turns the cursor into a ‘+’ for a drawing a line in your rendering. For more information, see Working with Lines.
Delete: Deletes the selected parameter.