I think you might have missed reading the whole content of the link.
I quote again, from the link I provided earlier:
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Contextually Apply the Action
Actions do not always apply in all situations, such as an action that is applicable only when the user selects a model. Therefore, you can specify one of the following contexts for your actions:
ModelContext
Indicates that the action should be available when the user selects a model. The format for this context is as follows:
<context>com.aprisma.spectrum.app.topo.client.render.ModelContext</context>
AlarmContext
Indicates that the action should be available when the user selects an alarm. The format for this context is as follows:
<context>com.aprisma.spectrum.app.alarm.client.group.AlarmContext</context>
TableContext
Indicates that the action should be available when the user selects any table. The format for this context is as follows:
<context>com.aprisma.spectrum.app.util.table.TableContext</context>
If no tablename is specified, context is limited to any table. However, you can also limit context to a single table using the following format:
<context>com.aprisma.spectrum.app.util.table.TableContext</context> <table-name>TableName</table-name>
You can specify one or a combination of contexts. If no specified context matches the current window context, the menu item is disabled. If no contexts are specified, the menu item is displayed in all contexts.
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In this section you specify where your custom menu must be displayed.