Using set_input_delay? When to use -add_delay, -rise, and -fall?

Hello, I was doing some research on the Multicyle Exceptions and found a great example:

http://www.altera.com/support/exampl...ulticycle_path examples


When I was looking over the example I decided to download the Quartus .qar archive. I then looked at the .sdc file and it was different that the example on the page.

For example the web page has:

#Constrain the input and output ports

set_input_delay -clock clk_in 1.2 [get_ports data_in]
set_input_delay -clock clk_in 1.5 [get_ports async_rst]
set_output_delay -clock clk_in 2 [get_ports data_out]



But the .sdc file in the .qar has:


#************************************************* *************
# Set Input Delay
#************************************************* *************

set_input_delay -add_delay -rise -max -clock clk_in 1.500 [get_ports async_rst]
set_input_delay -add_delay -rise -min -clock clk_in 1.500 [get_ports async_rst]

set_input_delay -add_delay -fall -max -clock clk_in 1.500 [get_ports async_rst]
set_input_delay -add_delay -fall -min -clock clk_in 1.500 [get_ports async_rst]

set_input_delay -add_delay -rise -max -clock clk_in 1.200 [get_ports data_in]
set_input_delay -add_delay -rise -min -clock clk_in 1.200 [get_ports data_in]

set_input_delay -add_delay -fall -max -clock clk_in 1.200 [get_ports data_in]
set_input_delay -add_delay -fall -min -clock clk_in 1.200 [get_ports data_in]

So here's my question, why is there a -add_delay and why is there a -rise and -fall? Are those required?

Thanks,
joe