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Compliance with ITU Z.100


The SDL Editor complies with the SDL rules as defined in the ITU Z.100 recommendation. Virtually all parts of the recommendation are supported by the SDL Editor. More information on the SDL support compared to Z.100, see Compatibility with ITU SDL.

Syntax Rules when Editing

Some of the SDL syntax rules are enforced during editing when you create diagrams, add pages to these diagrams, add symbols and lines to your pages and edit the text inside the symbols and lines.

Next follow the syntax checks that are performed by the SDL Editor:

Turning Syntax Checking On and Off

The syntax checking for entered texts, for what symbols you are allowed to use, and how you can interconnect symbols can be disabled and enabled again.

To disable or enable syntax checking:

  1. The operation applies on one diagram at the time. Therefore, make sure you are editing the correct diagram.
  2. Select the Diagram Options menu choice from the View menu. In the dialog which is issued, toggle the Layout Syntax Check and/or Textual Syntax Check button on or off and click OK.

Note: No Retroactive Syntax Checking

Turning the switch from off to on will not perform a retroactive syntax check for not allowed interconnection of symbols. Only the objects that you insert while syntax checking is enabled are checked. However, the syntax check on texts will be performed on all the texts when syntax check is set to on.

Syntax checking in Kernel Heading and Reference symbol

The syntax check for texts in the kernel heading or any reference symbol is always on independent of the diagram options setting.

Pasting and Syntax Checking

Only symbols that are valid according to what is displayed within the symbol menu may be pasted into a page. Non-valid symbols will be omitted whether or not syntax checking is enabled.

Identical Symbols - Different Syntax

SDL contains some symbols which appear identical, but are distinguished by their syntax. The symbols are:

  • The in connector and the out connector
  • The continuous signal and the enabling condition.

When layout syntax checking is on, the SDL Editor automatically determines from the context what kind of symbol it is. If syntax checking is off, the symbols are always treated as in connector and enabling condition, respectively.

Note: No Layout Check means Syntax errors

When disabling the layout syntax check and using connectors in the diagram mean that it will not be possible to analyze the diagram without errors as all connectors are treated as in connectors. Thus never turn off this switch if you want to analyze the diagram.

SDL Grammar Help

The SDL Editor provides a versatile context-sensitive support function - the Grammar Help window. The grammar help window is available to assist you when entering and editing the syntax of SDL text elements that are correct according to Z.100 definition. It simplifies writing statements with the correct SDL syntax.

The SDL Grammar Help facility is described in Using Grammar Help.

Signal Dictionary Support

The SDL Editor also provides a means of access to a signal dictionary where the signals that are already defined can be accessed. The Signal Dictionary window provides functions for listing SDL signals that are available when looking up or down in the SDL hierarchy or by looking at the current diagram. Also, you can ask the tool to list signals that are used in the current diagram or defined and visible according to the SDL scope rules.

Furthermore, the signal dictionary has the ability to import messages from a Message Sequence Chart (each MSC message will be mapped to an SDL signal) and to import an external signal dictionary.

For more information on this topic, see Using the Signal Dictionary.


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