Tcl Modules (TM, see TIP 189, http://tip.tcl.tk/189\) cannot be required from a safe interp.
% package require math::bigfloat
% interp eval interp0 "package require math::bigfloat"
can't find package math::bigfloat
% interp eval interp0 "package require math::linearalgebra"
can't find package math::linearalgebra
Since is a problem, since many of the important tcllib package are now provided through the TM mechanism.
The old versions of those packages are correctly loaded in the safe interp... but they are old versions !
According to Andreas Kupries, on the active tcl mail list:
"The code for the 'safe base' was likely not updated to handle searching for TMs... It may also be that the package unknown handler doing the search for TMs is not installed in safe interpreters. I would have to
check the init.tcl file doing that part of the setup."
"Remember, a big part of the 'package' command, the search for packages, is implemented in Tcl and plugged into the main command via 'package unkown'.
The relevant pieces of the core are in 'init.tcl', which sets up the plugging, 'package.tcl' handling the general package mechanism, and 'tm.tcl' for the Tcl Modules."