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About Symbols and Lines
Following is a description of the components in the drawing area. See also Symbols and Lines - Quick Reference.
The Additional Heading Symbol
The additional heading symbol is not defined further according to Z.100. In the SDL Editor, it looks like a dashed text symbol or it is shown without any border; this is controlled by the Editor preference ScreenZ100Symbols. The symbol is editable and resizeable, but cannot be moved. Its intended use is to define:
- Inheritance and specialization, using the following keywords:
- Formal parameters for a process / procedure, using the keyword FPAR
- Directives to the SDL to C Compiler. A directive uses the SDL comment notation and a hash character, such as:
/*#INCLUDE file.pr */- SIGNALSET and instance information.
The additional heading symbol is either repeated through all pages contained in an SDL diagram or it is only shown on the first page. This is controlled by the editor preference AdditionalHeadingOnlyOnFirstPage and can also be specified with the SDL Editor command Diagram Options.
Note that the combined text in the Kernel Heading and the Additional Heading symbol must use the syntax as specified for a heading in SDL/PR to be accepted in the SDL Analyzer.
The Package Reference Symbol
Z100: 2.4.1.2 Reference in Package Z100: 2.4.2 Reference in SystemThe package reference symbol is available on system and package diagrams only. It is located outside the frame, on top and to its left. It contains references to package(s) containing definitions that are to be included in the SDL system.
You can select and resize, but not move the package reference symbol.
Other SDL Symbols
These are the symbols that describe the structure or behavior of the SDL diagram. They must be placed inside the frame.
You can draw symbols in color, see Color on Symbols.
Syntax Checking on Symbols
The SDL Editor checks that the symbols you add to a diagram are in accordance with the syntactic rules imposed by SDL. Symbols that are not allowed in a diagram / page of a specific type are dimmed in the symbol menu. Also the text entered is checked for syntax errors. See Layout syntax check.
Symbols on both Interaction Pages and Flow Pages
Symbols on Interaction Pages
Symbols on Flow Pages
Graphical Properties of Symbols
You can select and move all symbols that are available in the symbol menu, and you can assign the symbols arbitrary locations.
You can resize certain symbols; these are indicated by filled selection squares. Other symbols can only be partially resized or cannot be resized at all1; this is shown by grayed selection squares.
No symbol is allowed to overlap any other symbol except the text symbol and the additional heading symbol.
Text / Additional Heading / Package Reference Symbols
The text, additional heading and package reference symbols look like a piece of paper. When all of the text within a text symbol is in view, the upper right corner is "folded" down. When any portion of the text within a text symbol cannot be seen (because the text symbol is too small), the upper right corner is clipped or diagonally cut off. See Figure 374.
Clipped text symbols are printed in their whole on a separate sheet of paper.
Comment / Text Extension Symbols
The comment and text extension symbols can be shown either in full size enclosing the complete text or clipped (collapsed) where the symbol is in the minimum size and only the first part of the text is visible. The clipped symbol is visualized as if the lower right corner has been cut off. See Figure 374.
Block Substructure Symbol
The appearance of this symbol differ from the drawing rules in Z.100. The non editable text "substructure" is drawn inside the symbol. Without this extra text it is impossible to distinguish the block symbol and the block substructure symbol by their visual appearance.
The appearance can be set to be according to Z.100 by the Editor preferences ScreenZ100Symbols and PrintZ100Symbols. Setting these to on means that the extra text will not be drawn or printed.
Symbol Text Attributes
Most SDL symbols have one or multiple text attributes. A text attribute should be filled with an SDL/PR expression (textual expression) that is syntactically correct according to Z.100. Depending on the correctness of the text, the SDL Suite tool set has the ability to perform the following operations:
Syntax Checking on Text Attributes
You are not forced by the SDL Editor to fill text attributes with text. However, a context sensitive syntax check is performed for each text attribute. The first located syntax error is indicated by a red bar underlining the text where the error occurs.
A global syntax check for the complete diagram is performed by the SDL Analyzer.
Reference Symbols
Diagram reference symbols allow to build an entire SDL system by referring to diagrams that are structurally related. Reference symbols are the following:
- Block reference
- Process reference
- Block substructure reference
- Service reference
- System type
- Block type
- Process type
- Service type
- Operator reference
- Procedure reference
- Text Reference
These symbols are handled by the SDL Editor in order to ensure consistency between the SDL diagrams and the SDL structure that is handled by the Organizer. Because of that, the SDL Editor imposes the restriction that a reference symbol must be unique within an SDL diagram (this restriction is not in conflict with Z.100).
You are permitted to have diagram reference symbols that are not assigned any name.
The SDL Editor performs a number of checks when you edit an SDL reference symbol. Furthermore, when you double-click a reference symbol, the SDL diagram that the symbol refers to will be opened.
See also Working with Diagram Reference Symbols.
Instantiation Symbols
You may use any of the following reference symbols for the instantiation of a type:
An instantiation symbol differs from a "normal" reference symbol in the sense that the syntax of the symbol's text differs. The syntax is:
a:a_typewhere a_type is the name of the SDL type diagram (block type, process type or service type diagram) that is instantiated into the diagram with the name a.
Instantiation symbols are visualized in the Organizer structure. The Organizer structure is updated to reflect the nature of the changes applied to the SDL diagram, in a similar fashion as for diagram reference symbols (see Reference Symbols).
The names of instantiation symbols must be unique within an SDL diagram.
See also Working with Diagram Instantiation Symbols.
Dashed Reference Symbols
Any of the following reference symbols may be dashed:
Dashed symbols are visualized in the Organizer structure. The Organizer structure is updated to reflect the nature of the changes applied to the SDL diagram, in a similar fashion as for diagram reference symbols (see Reference Symbols).
The names of dashed reference symbols must be unique within an SDL diagram.
See also Working with Dashed Symbols.
Lines
Lines are the graphical objects that interconnect symbols. One line only is available in the symbol box, namely the gate, which is handled as a symbol. You can insert it by selecting it and placing it into the drawing area.
You insert the other lines by selecting a symbol and dragging the handle that appears on the source symbol and connecting it to the target symbol. (Some symbols have multiple handles).
Lines are always connected to symbols, they are not allowed to exist on their own.
You can select, move and reshape lines. Some layout work is performed automatically by the SDL Editor.
A line is allowed to overlap any other object.
Lines in Interaction Diagrams
The following lines are defined in interaction diagrams (see Figure 376 and Figure 377):
You can reshape each of these lines and you can also move the connection points.
Lines in Flow Diagrams
On flow diagrams, the following lines are defined (see Figure 378):
Line segments on flow pages always use a 90-degree angle. You can add segments on a line, but connection points are fixed.
Syntax Checking on Lines
The SDL Editor checks that the target symbol is in accordance with the syntactic rules imposed by SDL. If not, the SDL Editor will refuse to connect the symbol. When you edit the text attributes are instantly checked for syntactical errors.
Textual Objects
Textual objects are the textual attributes that are related to a symbol or a line. Each of these attributes is prepared by the SDL Editor - you need of course to fill in their textual contents.
Textual attributes are indicated by a small rectangle which appears upon selection of the symbol or line the attribute belongs to.
You can select and edit textual objects. You can move them freely, as long as their location does not violate the rules defined by Z.100.
Textual objects are allowed to overlap any other objects.
Textual Objects in Interaction Diagrams
The following textual objects are defined in interaction diagrams:
Textual Objects in Flow Diagrams
In flow pages, the following textual attributes are defined:
Graphical Connection Points
Connection points are text objects which are created automatically by the SDL Editor when you draw a channel or signal route to the frame or to an instantiation symbol.
They are handled in a similar way as other text attributes. You are free to fill connection points on the frame or not. The alternative is to define textual connection statements between channels and signal routes in a text symbol.
Change Bars
A change bar is a vertical line to the left of a text in an SDL diagram. It visually identifies changes in the SDL system.
A solid change bar indicates that the text has been changed. A dotted change bar indicates that a text or its associated symbol has been moved.
The change bars associated with the diagram name and the page name act as change bars for the complete page. As soon as a change has been made to a page, change bars for the diagram name and the page name are added.
You can turn change bars on and off and also clear them from the Organizer. See Change Bars.
1The size of non-resizeable symbols is computed by the SDL Editor to fit the text contained in the symbol.
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