Optional fields
Message fields may be optional, which means they can be present or absent in a sent or received message. Standard optional fields have a square checkbox icon to the left of their field name: 
Choice fields
Some optional fields, known as choice fields, allow at most one mandatory choice from any set of choices. These fields have round (instead of square) icons: 
Field states
The state of an optional field determines its COUNT in the scenario definition, whether to include it when sending messages, and how it affects whether to match a scenario in received messages. The following table shows icon settings and their field’s corresponding COUNT in the scenario definition, whether the Simulator will include the field in that state when sending messages, and whether the Simulator will match the scenario for the field in that state when receiving messages.
| Icons | Setting | Count | Send | Receive | ||||
|---|---|---|---|---|---|---|---|---|
|
Mandatory |
1 |
Include. |
Only match if present. |
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|
Prohibited |
0 |
Do not include. |
Only match if not present. |
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|
Optional |
0..1 |
Do not include. |
Match if present; otherwise ignore. |
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(x..y) |
Non-standard COUNT |
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|
Absent |
Empty icons represent fields which are not present in the scenario definition at all. |
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Mandatory is the default state for new fields. |
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Click the icon to change between states. |
Translatable fields
Translatable fields provide different views of the same raw data. Selecting them will translate the data into the selected view. For a scenario to be valid, one (and one only) of the available translatable fields must be selected, by clicking the diamond icon to the left of the field name: 
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Usually a translatable field has an 'encoded' form and one or more 'structured' forms. |
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The selected translatable field for a scenario definition has a filled icon: 
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