(Answered) IO - Superheavy Mech Tech Base

[ANS Kamas P81]

Jihad Final Reckoning rules question.
Page 144, Construction Rules states "Superheavy BattleMechs and Superheavy IndustrialMechs are available only to the Inner Sphere Tech Base under these
rules."
Page 146, under Heat Sinks, states "This means that a Superheavy ’Mech can ft up to 2 standard (single) heat sinks per critical slot, or 1 Clan
double heat sink (if using Mixed-Tech rules)"
The apparent position is that Clan-tech DHS may be mounted as a Mixed-Tech machine, except that is apparently contradicted by page 144.  Is the implication correct that Clan-technology DHS can be used on an IS-Tech-Base machine (similar to the Pendragon MUSE RED from XTRO Davion) or is the specification of IS Tech Base meaning that the only construction options - Gyro, HS, Engine, IS, Cockpit, Armor, Myomers - must all come from within the IS Tech?  What defines a machine as being IS-Tech (and legal to build as a Superheavy) and not-IS-Tech (therefore not legal to build)?

I'd asked previously (in the Ask The Developers) about using Clan-tech weapons in pods on a Superheavy Omni, and the official answer was that it was allowable.  This would, as I understand the rules, result in a Mixed-Tech machine, or would it still be Inner Sphere as far as Superheavy construction rules?

If that is the case...what exactly can Superheavies be built with, and what are they absolutely never allowed to have? Any Clantech at all?

[Xotl]

This is the build vs. customize issue - namely, that you can only design/build superheavies as IS Tech machines, but once they've been built and are out in the real world you can do whatever you want to them, as per the normal customization rules, and suffering the usual mixed tech penalties that result.

However, note that superheavies are specifically limited in their construction rules to Industrial, Standard, Endo, or Endo-Composite Superheavy structure (Superheavy added to each designation).  So even with Mixed Tech, this still applies.