User guide

13-32
SDF Backannotation
The SDFPOLICY variable allows you to select the backannotation
delay value. You can set this variable to MIN, MAX, or MINOMAX.
The default value is MAX for backwards compatibility. If you specify
a value other than MIN, MAX, or MINOMAX, VCS issues a warning
and uses MAX as the default value.
INTERCONNECT Delays
INTERCONNECT entries in an SDF file are for backannotating delays
to a net that connects two or more module instance ports.
If that net has more than one driver, for example, when a net connects
more than one output port to an input port, you can use an SDF file
to backannotate different delays between the input port and each of
the output ports. Doing so is called backannotating multisource
INTERCONNECT delays.
If that net has only one driver, you are backannotating single source
INTERCONNECT delays. There is an option for multisource
INTERCONNECT delays that can be handy for single source
INTERCONNECT delays. See "Single Source INTERCONNECT
Delays" on page 13-36.
Multisource INTERCONNECT Delays
Figure 13-1 shows a multisource net, a net with more than one driver.