Why does the TimeQuest timing analyzer use the fast process-low temperature timing model by default when executing my custom Tcl script during compilation?

In the Quartus® II Software version 11.1 SP2 and earlier, the TimeQuest timing analyzer may use the fast process-low temperature timing model by default when executing a custom Tcl script during compilation.

If you require your custom Tcl script to run with a different timing model, use the set_operating_conditions Synopsys Design Constraints (SDC) command at the top of your custom script to specify which model to use.

In the Quartus II software version 12.0 and later, custom Tcl scripts use the slow process-high temperature timing model by default.