In 9.1.1 CPLDfit, the following warning occurs if the clock signal in the offset constraint does not have a BUFG constraint applied to it, and the OFFSET constraint is not analyzed:
"WARNING:Cpld:823 - Clock clk appearing in an OFFSET timespec currently must be explicitly declared as a global clock input (BUFG) in your design. The OFFSET constraint referring to this clock will be ignored."
To work around this issue, the user can apply the BUFG constraint.
For example (in the UCF):
NET "clk" BUFG=CLK;
For further information on the BUFG constraint, see the Constraints Guide.