Each hot spot type supports its own set of properties. These properties are defined by specific characteristics that determine how each property can be used. For example, the ContextID property of the Context ID hot spot type is a collection property. It accepts multiple values, allowing you to specify more than one context ID for a topic. Other properties, such as the Tag property of the Topic Link hot spot type, are simple properties, accepting only one value.

Below is a description of the types of properties and their characteristics.

Primary and Secondary Properties

We distinguish between two kinds of properties: primary and secondary. Primary properties are used to override the hot spot meaning of the primary part. Secondary properties simply provide additional information for the hot spot; they do not affect the meaning of the primary part.

For example, the Topic Link hot spot type has a primary property Tag, which is used to specify the target of the link. The following Topic Link hot spot does not use the primary property Tag; therefore, the primary part defines what the hot spot does:

This is a link to My Topic Link.

This hot spot jumps to the topic My Topic Link.

But suppose you would like the link to jump to a topic other than My Topic. You can use the primary property Tag to specify a different target:

This is a link to My Topic Link|tag=My Topic.

This hot spot sets the primary property Tag to My Topic; therefore, the primary part of the hot spot, My Topic Link, is ignored. Once a primary property is introduced, the primary part of the hot spot only defines the text that is shown in the target. The hot spot action is then determined by the value of the primary property, or Tag, in this case. This link jumps to the topic My Topic and not to My Topic Link.

If you were to add the Topic Link hot spot type's secondary property window to the hot spot, this property does not affect the meaning of the primary part, it only tells the link to open in a specific window:

This is a link to My Topic Link|window=proc.

This hot spot jumps to the topic My Topic Link, and it appears in the window named proc.

The order of property/value pairs in the secondary part of the hot spot is unimportant.

Default Properties

Almost every hot spot type has a default property. The name of a default property can be omitted from the secondary part of a hot spot. The corresponding ‘=’, however, must always be present, even for a default property. For example, here is a topic link with the Tag property set to a specific topic:

Here is a Topic Link|tag=My Topic.

Since Tag is the default property of this hot spot type, the topic link can be also be defined as:

Here is a Topic Link|=My Topic.

Either way is correct.

Simple and Collection Properties

A property can be a simple property, where each value is a single value, or a collection property, which can have a single value or a list of values.

The primary property Tag used in the examples above is an example of a simple property. You may specify only one topic as a target of a link. Tag does not accept multiple values.

A collection property value is a plus-separated list of values: “value1+value2+value3”. The ContextID property of the Context ID hot spot type is an example of a collection property, because it allows you to set multiple context IDs for one topic. For example:

My Topic|contextid=3+6

My Topic is assigned two context IDs, 3 and 6.

If a hot spot type supports a primary collection property, then its primary part is processed, only if this property is not set in the secondary part, according to the same rules as the primary collection property. In other words, it is also treated as a semicolon-separated list. The previous example can be rewritten as:

3+6

The primary part is 3+6, and the primary property, contextid, is a collection property; therefore, 3+6 is processed as a list. The topic containing this hot spot is assigned two context IDs, 3 and 6.

Case-sensitive and Case-insensitive Properties

Property names are case-insensitive. D2HML recognizes property names written in either upper or lower case. Property values may be case-sensitive or case-insensitive, depending on the property. See each property under the Hot Spot Types to determine its case-sensitivity.

For additional information on the different hot spot types and their properties, see Hot Spot Types.