Altera DDR Timing Wizard - Manual (Page 53)

Altera Corporation 2–41
November 2007 DDR Timing Wizard User Guide
Getting Started
generates two .tcl files with a .fast and .slow extensions to indicate
fast and slow timing model constraints, respectively, in addition to
the .sdc file, as shown in
Figure 2–29 .
Figure 2–28. Last Page of DTW with Both Fast and Slow Timing Model tcos Option