The Slot Form

The Slot Form can be used to define and edit the attributes of a slot. The Slot Form for the selected slot is displayed in the Slot Edit Pane at the right of the Slots Tab. The Slot Form can also be displayed as a free-standing window as follows: 

In the example below, the slot urgent for the class Article was double-clicked in the Template Slots pane. The slot form displays a Boolean Type, with Single Cardinality, and a text documentation pane of the urgent slot.

A slot can be used for more than one class. Each slot has a top-level (system) description; the system description can be specialized for a specific class. The scope of your edits depends on how you access the Slot Form. See Viewing a Slot for more information:

The Slot Form displays the following information for a slot:

  1. The Name of the slot.
  2. The Cardinality of the slot.
  3. The Value Type of the slot.
  4. (optional) Any Constraints that have been defined for the slot. 
  5. (optional) The Defaults that have been defined for the slot.
  6. (optional) The Minimum and Maximum values for the slot. These fields are only relevant to certain slot types.
  7. (optional) Any Documentation that has been entered for the slot.

For certain value types, an additional pane appears below the Value Type pane:

  1. For type Class, the Allowed Parents pane appears.
  2. For type Instance, the Allowed Classes pane appears.
  3. For type Symbol, the Allowed Symbols pane appears.

Slot Name

You can edit the slot name directly in the Name field. Slot names are case-sensitive. A recommended convention is to make slot names lowercase, and with words separated with an underscore (_). 

Cardinality

The Cardinality field allows you to specify whether the slot value may be composed of more than one item. 

Value Type

The Type of the slot determines the kind of values that the slot may hold. The available types are summarized in the following table:

Type

Description

Examples

Any Any of the types below (logical Union)  
Boolean Logical Value True, False
Class Class in the knowledge base Organization
Float Number with a decimal point 1.0, 3.4e10, -0.3e-3
Instance Instance of a class in the knowledge base instance_00010
Integer Whole number 1, 2, -4
String String of alphanumeric characters, possibly including spaces "John Doe"
Symbol List of values, which may not include spaces red, blue and green

For a full description of the types, see The Value Type Menu

Constraints (optional)

Class constraints are defined programatically. See Constraints for more information.

Defaults (optional)

Allows you to specify the default value(s) for a slot. When an instance is created for a class that has a slot with a defined default, the default value is automatically entered as the value of the slot. The default value can then be changed or overwritten.

For a slot with Single cardinality, Defaults must be a single value or no value; for a slot with Multiple cardinality, Defaults can be more than one item.

When present, any Defaults are displayed in the second-to-last column of the Template Slots pane in the Classes tab.

Minimum (optional)

This field is applicable only to slots of type Integer or Float

Minimum allows you to specify a minimum value for your slot. When an instance is created for a class with this slot, the value of the slot must be greater than or equal to the minimum. For example, a minimum of zero means instances cannot have negative values. Together, Minimum and Maximum can be used to define an allowable range. 

When present, the Minimum value is displayed in the last column of the Template Slots pane.

Maximum (optional)

This field is applicable only to slots of type Integer or Float

Maximum allows you to specify a maximum value for your slot. When an instance is created for a class with this slot, the value of the slot must be less than or equal to the maximum. Together, Minimum and Maximum can be used to define an allowable range. 

When present, the Maximum value is displayed in the last column of the Template Slots pane.

Documentation (optional)

The Documentation field allows you to enter a text description of the slot. Filling in this field is optional but is recommended to make maintaining the knowledge base easier.

See The Slot Buttons and The Template Slot Buttons for the operations you can perform on slots.

Viewing Several Slots

To view the information for several slots at once, select the slots at the Slots Tab and click the View slot button to open the Slot Form for each class. To highlight multiple slots, hold down the Ctrl key while clicking each slot. To highlight a range of slots, click the first slot, then hold down the Shift key and click the last slot in the range. You can also view multiple slots using the Top-Level View or Class-Level View template slots buttons in the Template Slots pane.

Opening a new slot form does not close the previous form. This allows you to compare the attributes for two or more slots. Edits can be made directly in any open form.

If you have multiple forms open, you can manage them as follows:


Next: The Value Type Menu

Slots Table of Contents