The value reported by the detailed constraint for clock nets that use non-dedicated resources is different than the value reported by the data sheet in the TWR file.
Which value is correct?
The reason for this difference is that the detailed constraint report does not automatically analyze the clock skew for clock nets that use non-dedicated resources. The data sheet report of the TWR file will automatically address the clock skew on such clock nets.
In order to include the clock skew in the detailed constraint report for clock nets that use non-dedicated resources, use the "-skew" option.
NOTE: For clock nets that use dedicated resources (global or low skew lines), clock skew will be automatically addressed in the detailed constraint report.