A difference of opinion came up in game play about Alchemy, but it could involve any Skill that has both Techniques and a TL.
By the Book
Using Techniques (B 230) says "Unless noted otherwise, all
general modifiers to a skill - for...tech level (p. 168),and so forth - apply to its techniques, as do any special critical success or failure results."
Double Defaults and Techniques (B 232) says, "A skill cannot default to another skill known only by default (see
Double Defaults, p. 173). However, techniques are not skills. If two techniques are based on the same underlying skill, one
can default to the other, even if you only know the intermediate technique at default."
While Alchemy has a TL level, TL is not mentioned for Elixirs (Techniques).
Example
An Alchemist with Alchemy Skill 16 (TL 3) knows Regeneration (Technique) at Alchemy-1 or 15. He tries using a TL 4 lab, and is at -5 to Alchemy because of the TL difference, and thus is at -6 (-5 for TL difference and -1 for Technique level) for Regeneration. While using a TL 4 lab, his level is 11 for Alchemy (TL 4) and 10 for Regeneration.
But let's say he studies and gets TL 4 Alchemy at the same level he had it at TL 3, so he now has Alchemy Skill 16 (TL 4). He does nothing to increase Regeneration.
Question
If the Alchemist now uses a TL 4 lab, does he make a Regeneration Elixir at 15 (based on his Alchemy Skill 16 (TL 4) -1 (Technique)) or 10 (based on his Alchemy Skill 16 (TL 3) - 5 (TL difference) -1 (Technique))?
I'm assuming the answer to that would apply to any Skill with both a Tech Level and a Technique.