The loss of a message, i.e. the case where a message is sent but not consumed, may be indicated by a black hole.
Symmetrically, a spontaneously found message, i.e. a message which appears from nowhere, can be defined by a white hole.
{ <lost message area> | <found message area> }
{ is followed by <general order area> }*
{ is attached to <general order area> }*
<lost message symbol> is associated with <msg identification>
[ is associated with { <instance name> | <gate name> } ]
is attached to <message start area>
NOTE: The <lost message symbol> describes the event of the output side, i.e. the solid line starts on the <message start area> where the event occurs. The optional intended target of the message can be given by an identifier associated with the symbol. The target identification should be written close to the black circle, while the message identification should be written close to the arrow.
<found message symbol> is associated with <msg identification>
[ is associated with { <instance name> | <gate name> } ]
is attached to <message end area>
NOTE: The <found message symbol> describes the event of the input side (the arrowhead) which should be on a <message end area>. The instance or gate which supposedly was the origin of the message is indicated by the optional identification given by the text associated with the circle of the symbol. The message identification should be written close to the arrow part.