3.1.2. Drawing a reaction step rule

Charges are assigned to expressions in the same way described under 3.1.1 Drawing formulas they are assigned to symbols.

To draw a line between symbols or expressions, first choose the appropriate operator from the menu Rules, if one is needed, then select one end by pressing the mouse button with the cursor at less than 8 pixels from it and successively release the mouse button with the cursor at less than 8 pixels from the second end. A pop-up menu appears from which the bond can be chosen to complete the line (provided the line's distance from all previously drawn expressions is at least 20 pixels).

Notice that a single bond between an expression like + | s, where s is not a charge, and the expression p means that either + is assigned to p or there is a single bond between p and s. Similarly a single bond between an expression like . | + and the expression p means that either an electron or + is assigned to p.

The operators that can be chosen from the menu Rules to place an expression have the following meaning: The asterisk * matches any bond. A dashed line (long dashes)
appears on the window area.

not excludes exactly the bond chosen in the pop-up menu. A dashed line (short dashes)
appears on the window area, aligned with the chosen bond. The dashed line alone is displayed, if no bond is chosen. If, for example, the selected bond is single the line
is displayed on the window area.

greater includes exactly the chosen bond and all bonds with a higher valence, if the chosen bond is double or triple. As many dashed lines (short dashes) appear as the valence of the chosen bond. If double is chosen, the line
is displayed.
If triple is selected,
appears on the window area.

Notice that greater when no bond is chosen from the pop-up menu, is the same as the asterisk, when single is chosen, is the same as not completed by no bond and when quadruple is chosen, is the same as selecting quadruple without any operator from Rules.

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