As far as I am concerned, the documentations of time limits could be improved
Especially, the fact that time limits must be given in "absolute time" is not very clear.
When reading carefully the current doc, I really thought that time limits had to be given in terms of "time since the interpreter was created".
An example would help, such as :
% interp limit testlimit time -seconds [expr [clock seconds] + 10]
sets the time limit 10 seconds in the future
Also, in the text, it could be said that the limit will be reached when the current time (given by the clock command, or Tcl_GetTime) will reach the time limit.