There is a requirement for changing the message flow (A connection between sending and reciveing applcaition) color to RED depending on a attribute Business Critical Dependencies Details(BCD) of the message flow. The BCD attribute have 2 options- Yes or No. The color of the message flow should be red if the BCD attribute is set to ‘Yes’ and if BCD="No", it will show default color of message flow.
I suggest that ou create specific DiagramTypeLinkStyle for each possiblity, and connect them to the DiagramTypeLink in question of the DiagramTypeParam associated to the DiagramType you are wanting to modify. Each of these DiagramTypeLinkStyle is associated to a DiagramTypeLinkStyle Condition (in form of an attribute test, link test, or query test). On a DiagramTypeLinkStyle, it is possible to indicate the line style and brush style and colors.